List of The Big Bang Theory episodes (season 5)

Raj finds himself in hot water with Leonard and Howard after supposedly sleeping with Penny and the latter discovering his fantasies about Bernadette (who also became angry at Raj because of his fantasies, and now has to contend with Howard's feeling of distrust of her as a result). Raj and Penny later talk and it turns out they didn't have sex because Raj ejaculated prematurely when Penny tried to help him put on a condom. Nonetheless, Penny feels that this has damaged her relationship with the guys permanently and decides to move back to Nebraska, as she has not had any worthwhile acting jobs since moving to Pasadena. When she comes over to apologize and announce her intention to move, she gets a call from her agent, informing her that she got a part in a hemorrhoids commercial, prompting her to scrap her plans.

Meanwhile, after trying to figure out what Penny meant by "It's not what it looks like." (from the season 4 finale), Sheldon has appointed himself the captain of the guys' paintball team. When they are at another of the university's tournaments where they fight against other departments, their team falls apart because of Leonard, Howard and Raj's lack of enthusiasm due to everything that has gone on with Penny. Sheldon, blaming himself, puts down his paintball gun and walks outside, proclaiming that geology isn't a real science. Following that, he is promptly shot several times by the geology team. Leonard, Howard, and Raj immediately rush out to avenge Sheldon's "sacrifice" and even manage to claim the victory for the physics team.

Recurring character: Christine Baranski as Dr. Beverly Hofstadter

Priya has returned to India and she and Leonard are attempting a long-distance relationship. Their first time having cybersex is ruined when Leonard's screen freezes. Leonard then takes advice from Howard on how to maintain such a relationship and then prepares to perform one of the things he taught him, but is humiliated to learn that Priya's parents are sitting beside her. Meanwhile, Penny picks up a new chair, which at first Sheldon thoroughly likes until he finds out that she picked it up off the curb. He begins to harass Penny to dispose of it, resulting in many rejections. Sheldon then enlists Amy to try and coax Penny to get rid of it, but this only alienates Amy from Penny. Fearing her friendship with Penny is over, Amy sits on the chair to show her loyalty. She is then bitten by something moving in the chair, causing her and Penny to flee the apartment. Penny then tosses the chair, but Howard and Raj find it and bring it up to Leonard and Sheldon's apartment, as Raj doesn't want to sit on the floor all the time. Unbeknownst to them, the unidentified creature is seen moving again while they carry the chair up to the apartment.

Recurring characters: Aarti Mann as Priya Koothrappali, Brian George as Dr. V. M. Koorthrappali and Alice Amter as Mrs. Koothrappalli

After the entire group leaves Leonard and Sheldon's apartment following dinner, Amy stays behind while Leonard works. Her presence makes Leonard uncomfortable, telling him that she has been told she has a tendency to overstay her welcome. She later asks Leonard to accompany her to a friend's wedding, as Sheldon's past behavior at such gatherings makes him a poor date. At the wedding, Leonard is depressed at the state of his relationship with Priya, to which Amy retorts that her boyfriend is at home playing with model trains, and convinces him to dance with her. Meanwhile, after Bernadette tells Howard that she refuses to move in with him and his mother after they get married, he asks her to stay over for the weekend as a trial run. Bernadette agrees, but is horrified at aspects of Howard's relationship with his mother. Arriving home, Leonard is revealed to have strained a muscle in his groin, which was eased by ice given to him by Amy. When Leonard later ends their evening together by kissing her on the cheek, Amy fears Leonard has fallen in love with her, and goes to Penny for advice. Amy sends Leonard an email clarifying that she does not have feelings for him, but when Leonard relates the events of the wedding to Sheldon the next morning, including the incident with his pulled groin, Sheldon incorrectly understands that they had sex, and becomes jealous and hits Leonard, saying, "She is not for you! Not for you!" When Bernadette serves Howard breakfast in bed that morning, she says that communication with her mother is a bit tricky, on account of how different the two women are, and launches into a back-and-forth series of exchanges with Mrs. Wolowitz in which Bernadette imitates Mrs. Wolowitz's voice and accent perfectly.

Recurring character: Carol Ann Susi as Mrs. Wolowitz

After playing Dungeons & Dragons with the others, Sheldon decides to let the game's dice make trivial decisions for him from now on, so his mind is freed up for more important things. Although this allows him to get some important work done more efficiently, it also results in eating things he wouldn't normally eat, and other odd decisions, such as growing a moustache. Meanwhile, Penny sets Raj up with her deaf friend, Emily (Katie Leclerc), for whom his selective mutism is no longer an issue. He immediately takes a liking to her, although he requires Howard as a communicator at first. When Howard and Penny realize that Emily is exploiting Raj for all the expensive things he buys her with his parents' wealth (which Sheldon reveals to the others is far greater than they all previously realized), they attempt to talk to her. Howard is distracted by a couple of females, loses the trail of the conversation and ends end asking her directly if she was a golddigger. She is very offended at the intrusion. Penny then contacts Raj's parents, who threaten to cut off his allowance if he does not break up with her. When Raj chooses to remain with Emily, and tells her that they're going to return the expensive gifts he bought her, Emily breaks up with him. After commiserating with his friends at the Cheesecake Factory, they leave the bill with Raj, and Penny warns him not to be cheap with tip, as they now know how much money he has.

Recurring characters: Brian George as Dr. V. M. Koorthrappali and Alice Amter as Mrs. Koothrappalli.
Guest star: Katie Leclerc as Emily

When Leonard accepts an invitation by Wil Wheaton to a party at his house, Sheldon, who regards Wheaton as one of his mortal enemies, sees this as an act of betrayal on Leonard's part, a sentiment not mollified when the invitation is extended to Sheldon himself. Sheldon relents when told that Brent Spiner is at the party, and attends. At the party, Wheaton gives him a signed, mint-in-box Wesley Crusher doll (whose denial to Sheldon years earlier at a convention at which Wheaton failed to appear was the origin of Sheldon's animus towards Wheaton, as explained in "The Creepy Candy Coating Corollary"), bringing an end to Sheldon's enmity with him. When Brent Spiner impulsively rips open the package, however, an infuriated Sheldon places Spiner on his mortal enemies list. Meanwhile Howard is ecstatic to learn he will be traveling to the International Space Station as a payload specialist to assist in the implementation of a deep space telescope designed by his engineering team, but Bernadette, who worries about Howard traveling into space, and is angered that he did not discuss it with her before making his announcement, angers him by telling his mother, who forbids him from going.

Recurring characters: Wil Wheaton as himself, Kevin Sussman as Stuart Bloom and Carol Ann Susi as Mrs. Wolowitz
Guest star: Brent Spiner as himself

Sheldon's mother, Mary (Laurie Metcalf) is in town for a visit, but when she decides to accept Leonard and Penny's invitation to go sightseeing instead of attending watching Sheldon embarrass Nobel Prize laureate Saul Perlmutter at a lecture, Sheldon becomes irate at her. Amy counsels Sheldon that while he is a genius, his emotional reactions to his mother's ignoring him are no different from that of any other human being, and that the less intelligent might be able to handle their emotions better by not overthinking them. Sheldon, after being caught in the rain, returns home with a common cold, prompting his mother to nurse him back to health.

Recurring character: Laurie Metcalf as Mary Cooper

A successful Halloween prank from the group enrages Sheldon, who promptly starts working on his revenge. His efforts all end up being fruitless, as Sheldon pranks are too obvious, prosaic, and hampered by his inability to effect guile or deception. He eventually seems to have succeed in tricking Howard with an electric handshake. When Howard breaks down because of a heart condition, Sheldon is terrified. Bernadette orders him to inject adrenaline into Howard's heart. After doing so, he is astonished to find out that it all was a ruse by Howard and Bernadette. While wondering how he could have fallen for this, Sheldon then ends up shocking himself. Meanwhile, Leonard meets a good-looking female comic book enthusiast called Alice (Courtney Ford), but is torn by whether to be loyal to Priya or cheat on her with Alice. When in the middle of a romantic embrace with Alice, he confesses that he has a girlfriend, Alice throws him out. When Leonard subsequently relates these events to Priya, she appears to accept this, but when she reveals that she had sex with her ex-boyfriend a couple of weeks ago, Leonard becomes upset and ends the call. As he sits on the living room couch, Sheldon leaps out from under the couch cushions in zombie face paint, scaring Leonard. He triumphantly shouts "Bazinga, punk! Now we're even!"

Recurring characters: Aarti Mann as Priya Koothrappali and Kevin Sussman as Stuart Bloom

Amy is hurt to discover that Bernadette and Penny tried on bridesmaid dresses without her. When Sheldon tries to counsel her, she requests that they have sex, but they settle on cuddling, an experience Sheldon dislikes. When Penny and Bernadette learn of this, they are guilt-stricken, and attempt to apologize, but Amy is unyielding. Leonard and Sheldon later pick up a drunk Amy from the parking lot of a liquor store. She tells them that she drowned her sorrows in wine, and makes sexual innuendo with Sheldon. Penny and Bernadette try to apologize to her again. Bernadette finally succeeds by asking Amy to be her maid of honor, which she joyfully accepts because of all the wedding work to come (including Bernadette's bridal shower and bachelorette party). The episode ends with Amy taking a video of them trying on dresses together also catching Penny in her underwear.

Leonard accepts an offer to go on a platonic date to the movies with Penny, but when he refuses to exhibit the familiar deference to her that he formerly displayed to her as her boyfriend to make her amenable to sex, such as which movie to see or paying for both of them, the friction this causes leads to a war of oneupmanship throughout the evening. When they get home, Penny reveals that she actually likes Leonard's more assertive demeanor, which Leonard manifests in the belief that he may get sex after all, but he ruins his chances by reverting at one point to his more timid personality. Meanwhile, Sheldon, who suffers from ornithophobia, is upset when a large bird sets up a nest on the apartment windowsill, and and later flies into the apartment and perches on Sheldon's spot on the couch. Amy and Bernadette encourage Sheldon to try to overcome his ornithophobia. Sheldon manages to do so, and becomes smitten by the bird, and wishes to keep it. When he opens the window to get the bird's nest, however, it flies out, devastating him. He later reveals that the bird had laid an egg in its nest, of which he is going to take care.

When Amy visits the comic book store with Sheldon, Stuart, after inquiring about the state of her relationship with Sheldon, asks her out. When Sheldon later learns that Amy and Stuart are out on a date, Sheldon becomes jealous. After talking to Penny, he interrupts Amy and Stuart on their date, and asks Amy to be his girlfriend, which she gladly accepts. When Sheldon presents her a "relationship agreement", she is delighted and calls it very romantic, though she later feels that she should've consulted a lawyer over the agreement's stipulation that as a girlfriend, she must take care of her boyfriend's injuries. Meanwhile, the guys find out that a new expansion pack for Mystic Warlords of Ka'a called Wild West and Witches has come out, which they initially turn down because of its theme and the price, but eventually buy after an argument about who would win in a fight between Billy the Kid and the Wizard of the North. Leonard also tries to return the expansion pack, but Raj buys the Deluxe Limited Edition of the pack in a collector's tin. Leonard once again turns it down, but then ends up buying it, while being annoyed with himself for doing so.

Recurring character: Kevin Sussman as Stuart Bloom

Leonard is contacted by Jimmy Speckerman (Lance Barber), a former high-school classmate who bullied him on a regular basis, with a potential business proposition. When they meet, Speckerman greets Leonard like an old friend. He then proposes to make glasses that turn all movies into 3D. Sheldon confronts Speckerman for Leonard presenting him with Leonard’s complaint list. Speckerman is shocked by the list and later arrives at Leonard's apartment drunk and apologetic. The next morning he belittles Leonard’s grudge causing Leonard to order him out of the apartment. After being shoved by Leonard, Speckerman chases Leonard and Sheldon out of their own apartment. Meanwhile, Amy and Bernadette, while hanging out in Penny's apartment, discuss their own trouble with bullies. Penny mentions having pranked a girl by tying her up and leaving her in a cornfield, revealing that she was a bully herself. After trying to make amends by calling the people she bullied to apologize, she is rebuffed in the attempt. Instead she decides to give away some of her clothes that she no longer wants to make herself feel better. While dropping off her clothes, Penny takes some of the used clothes that she likes from the donation container, only to go back and return them the next day. Bernadette, however, runs back to collect a pair of shoes she liked, justifying her actions by the fact that she works at a soup kitchen.

Guest star: Lance Barber as Jimmy Speckerman

Amy and Sheldon's relationship hits a snag when she reveals that an article she wrote is on the front cover of a prestigious science journal, but he simply fails to respond, causing her to leave in a huff. After being questioned by Penny, he reveals that it is because he cares nothing for biology that he didn't congratulate her. Sheldon tells Penny he can't fake smile as the smile he uses is for when he sees a koala, which Amy has seen. Over a game of Red Dead Redemption with Leonard, Sheldon tries to think of a way to make it up to Amy, and Leonard suggests that he buy something for her. Sheldon agrees and purchases a diamond tiara from a jewelery store (and a pocket watch for himself) with the help of Penny. Amy, initially insulted, becomes ecstatic when she sees the tiara and forgives him at once, exclaiming "I'm a princess!", giving a big kiss and hugging him tightly.

Meanwhile, Howard and Bernadette's relationship also hits a snag when, while giving a magic show at a child's birthday party, Bernadette reveals she doesn't like children (having been forced to look after her brothers and sisters when she was younger). This upsets Howard, who wants children of his own, and whose mother has been nagging him to give her a grandchild for years. He even contemplates breaking up with Bernadette, although Leonard immediately advises against it. Eventually, Bernadette suggests that, as she earns more than him, she work and Howard look after the kids. Howard, though slightly perturbed by her remark and the prospect of having to look after children on his own, agrees.

Recurring character: Carol Ann Susi as Mrs. Wolowitz

Upon arriving home, Sheldon discovers that the cutout of Mr. Spock he ordered is of Zachary Quinto, not Leonard Nimoy. As he gripes about this, Leonard notices Penny across the hall, and spontaneously asks her out on a date. Penny complains to Amy and Bernadette about being nervous over their date. Their dinner starts well, but soon goes sour when Leonard insists on over-analyzing their relationship. He comes home in a bad mood, causing Howard and Raj to assume he and Penny are on the outs. However, that night, Penny invites him over via text, and, after warning him not to talk, they have sex. They agree to keep their relationship secret. When everyone has dinner at the Cheesecake Factory, Leonard overplays his fake annoyance, genuinely angering Penny. They have a late-night argument, followed by more sex. Leonard tells Penny that he cannot imagine this ending well, to which she responds that it's because he over-thinks things.

The scene shifts back to the hallway, with Sheldon still grousing about Spock – the whole episode was in Leonard's imagination. Realising he does over-think things, he marches into Penny's apartment and asks her out. She asks if he's thought this over, and he replies that he has, but that they should go anyway. She agrees as a smile comes to her face. The episode ends with Penny preparing for her date with Amy and Bernadette. When asked a question, though, she is distractedly imagining herself very pregnant and marrying Leonard, which reminds her to stop by the drugstore before the date.

Leonard and Penny have started dating again. Anxious to avoid the mistakes of last time, Leonard suggests they have an Alpha test relationship: rather than getting angry with each other, they'll simply report any 'bugs' they discover and fix them. This goes poorly due to Leonard giving Penny an insultingly long list of her faults, although she remains calm about it. When he tries to patch things up by taking her target shooting, he accidentally shoots himself in the toe. Afterwards, Penny reassures Leonard that their relationship is progressing smoothly.

Meanwhile, Sheldon and Amy start a podcast series about flags. Amy makes suggestions about their telecast which Sheldon accepts out of character indicating a close bond between them.

Raj gets an iPhone 4S and falls in love with its virtual assistant, Siri. He takes Siri on dates including a dinner party with Howard and Bernandette which the two of them find very creepy. Kripke reveals he has the same model phone, but his speech impediment (rhotacism) leads to Siri making some humorous errors.

Recurring character: John Ross Bowie as Barry Kripke
Guest star: Becky O'Donohue as Siri

After Sheldon keeps him up all night with a quarterly disaster preparedness drill, a tired Leonard is furious and refuses to take Sheldon to his various appointments. Sheldon reminds him of the roommate agreement and his duties listed in the document, but also tells him about a clause that reduces them to mere acquaintances and, when agreed upon, relieves Leonard of all obligations except for payment of rent and utilities. Leonard happily accepts and signs so that he can go home and get some sleep. It turns out that Sheldon is stranded without Leonard, as none of his other friends are willing to help him. During a power outage, Sheldon tries to win Leonard back with his extensive emergency kit, but the latter prefers to go over to Penny's apartment for wine. As they are about to make out, an upset Sheldon storms in and offers Leonard s'mores and water distilled from urine if he is willing to come back. When Leonard declines again, a sad Sheldon walks away. Pitying him, Penny sends Leonard to rekindle their friendship. Leonard is willing to do so, as long as Sheldon shows some appreciation when he does him a favor. Instead, Sheldon offers to celebrate 'Leonard's Day' once a year, honoring his selfless actions. After Leonard agrees, it is revealed that Sheldon caused the power outage. 'Leonard's Day' turns out to be nothing more than the receipt of a cheap greeting card.

Meanwhile, Howard is anxious to see what astronaut nickname his new colleagues will choose for him. Raj attempts to get them to choose 'Rocket Man' by having Howard change his ringtone to that song and then calling him during a conference call with Mike Massimino. This backfires when Howard's mother bellows that his Froot Loops are getting soggy, and he ends up with 'Froot Loops' as his new moniker.

Recurring characters: Kevin Sussman as Stuart Bloom and Carol Ann Susi as Mrs. Wolowitz
Guest star: Mike Massimino as himself
Title reference: Leonard and Sheldon's relationship is reduced from friends to mere acquaintances.

Sheldon is forced to take a vacation by the university president. After trying to sneak into work, Sheldon goes to help Amy in her biology lab. She has him cleaning laboratory glassware and counting growth cultures in Petri dishes and failing at both tasks. Sheldon insists that with his intelligence he can do more. When Amy lets him try to dissect a brain, he faints after he cuts his thumb. He ends up at a bar, drinking virgin piña coladas at the Cheesecake Factory bar with Howard.

Bernadette's father wants Howard to sign a pre-nuptial agreement which he unfortunately hears about through the "nerdvine". He's reluctant to sign, and tells her that he'll go talk to her father himself. When Bernadette explains her father still carries his police revolver and has a violent temper as well as dislikes that include Jews, he decides to put off the discussion until after he's up on the International Space Station – noting "they got a phone".

At The Cheesecake Factory bar, Penny sets both Howard and Sheldon straight. She tells Howard how lucky he is to have Bernadette and he should sign anything put in front of him. Sheldon gets scolded for fainting at the sight of a little blood. He claims that it is not a little cut and then faints again after showing it to Penny. Afterwards, Sheldon returns to Amy's lab, where she wants to hear him apologize for his behavior. After she shoots down a few Sheldon-esque efforts to couch his apologies in superior and/or insulting terms, Sheldon finally and genuinely says "I'm sorry". Amy accepts it and tells him to get back to his cleaning tasks, leading Sheldon to mutter that his next vacation period will definitely see him heading to EPCOT.

Recurring character: Joshua Malina as President Siebert

When the deranged Professor Rothman is forced to retire, both Sheldon and Kripke vie for his office. President Siebert refuses to resolve the dispute, so Leonard arranges a one-on-one basketball game to decide (since they're both equally bad at sports). Neither one can even make a single basket, so they end up deciding by seeing who can bounce the ball the highest. Sheldon wins; unfortunately, the office is not what he'd hoped for: there is a hole in the wall, the thermostat is located in the office of a professor going through the hot flashes of menopause (thus Sheldon is too cold), the mockingbird outside his window is off-key with the annoying windchimes, the perpetually naked Professor Rothman refuses to vacate, and the Geology Department upstairs makes too much noise. Finally, Sheldon gets his head stuck in the wall, as his scientific curiosity made him want to know what's inside. Leonard comes by and agrees to help him, but instead takes a picture of Sheldon's unfortunate situation.

Penny is dismayed when Amy gives her a gift: a gargantuan painting of the two of them, which portrays Penny unflatteringly. With no good way to avoid displaying it, and to avoid hurting Amy's feelings, she only hangs it up when Amy is over. When Amy catches her taking the painting down, she's embarrassed and angry and takes the painting away. When Penny finds out the painting cost Amy $3000, Penny lies and says she removed the painting to spare Bernadette's feeling over being excluded from the deep bond between the "besties". However, Amy says "she's just lucky we let her hang out with us" and brings the painting back to Penny's to hang it up. It ultimately ends up on the "fourth wall" of Penny's apartment, out of view of the television audience.

Recurring characters: John Ross Bowie as Barry Kripke and Joshua Malina as President Siebert
Guest star: Lynn Phillip Seibel as Professor Rothman

Sheldon refuses to let anyone cut his hair except for his regular barber, even going to see his barber in the hospital and trying unsuccessfully to talk him into coming out of his coma. Penny offers to trim his hair because she use to cut her brother's but he declines. Penny later tells him to embrace the chaos and that it just might be fun not knowing what will happen next. Sheldon agrees to her proposal and decides to wear his Tuesday pajamas on Thursday night and takes up playing bongos in the middle of the night. After objections by Leonard and Penny he ends up on Amy's couch. With Amy's vote of confidence, Sheldon agrees to Penny cutting his hair, which she messes up at the end of the episode, unbeknownst to Sheldon.

Meanwhile, after his first day of training, Howard video chats with Bernadette and describes his experiences at NASA. One day he vomits during zero G training and another day he has a horrible survival test experience. After seeing how much trouble he is having, she flies to Houston to help take care of him and finds his mother already doing that.

Penny also beats Leonard at chess despite having almost no idea what she's doing or what the different pieces are called. Leonard is mildly annoyed but both he and Penny quickly forget the issue when they have to deal with Sheldon's odd behavior that includes letting Penny sit on his spot on the couch.

Recurring characters: Carol Ann Susi as Mrs. Wolowitz and Vernee Watson as Althea
Guest star: Peter Onorati as Angelo

Raj suggests the four guys have a Star Wars online video game marathon; however, Sheldon had promised to attend a birthday party for Amy's aunt. Sheldon wants to stay, but agrees to stick with his commitment to Amy. Howard on the other hand invites Bernadette to join their marathon. Sheldon tries unsuccessfully to get Penny to talk to Amy into changing her mind. When Amy picks up Sheldon, he has his computer and plans to play along remotely. Amy is unhappy, but tells him to go join the gang. Later she shows up at Penny's confiding about her boyfriend. She told Penny that she wanted to show her family that she had a real boyfriend and not one of her imaginary ones. After a couple of suggestions including withholding sex that wouldn't work with Sheldon, they decide for Amy to make a scene in Sheldon’s apartment. Instead Raj stands up and complains that he wanted the guys to get together like they used to before everyone else had girlfriends. Raj then reveals his weekend plan was concocted because he is the only one of the four guys who doesn't have a girlfriend. When the guys assure him that he'll someday start a relationship with a woman, Raj bemoans the fact that even if he does, it will be "after Sheldon Cooper!" Penny tells Amy that that is the way a girl makes a scene, and the girls leave the guys alone. The next day, the game fest ends when Howard’s mother bangs on the door demanding an explanation for Howard's not being home.

Recurring characters: Carol Ann Susi as Mrs. Wolowitz and Kevin Sussman as Stuart Bloom

When Sheldon complains about Penny constantly mooching their food, she buys both Leonard and him a mint, in the box 1975 Star Trek transporter toy. She's disappointed when they refuse to take them out of the boxes to preserve their value. That night Sheldon dreams his Spock action figure (voiced by Leonard Nimoy) declares it illogical to own a toy that does not get played with. When Sheldon awakes, he joyfully opens the transporter and promptly breaks it. Sheldon immediately switches it with Leonard's hoping he won't be found out since Leonard was not planning on opening his toy. Later Sheldon has a nightmare about being chastised by his toy Spock about his actions and being attacked by a Gorn. When Leonard decides to play with his toy since it was a present from his girlfriend Penny, Sheldon is forced to confess that he broke it and return Leonard's property.

Meanwhile, Raj, depressed at the prospect of attending Howard's wedding alone, asks his parents to find him a potential wife. He hits it off with the new girl until she admits she is a lesbian, looking for a sham marriage to cover her homosexuality, and that she assumed Raj was also gay. Raj contemplates going through with the marriage, feeling as though he will never find someone, who is not gay, that actually loves him. To cheer him up, Howard and Bernardette get him a female Yorkie puppy.

Recurring characters: Brian George as Dr. V. M. Koothrappali and Alice Amter as Mrs. Koothrappalli
Guest stars: Chriselle Almeida as Lakshmi, Leonard Nimoy as Spock (voice)
Note: This is the first time that Leonard Nimoy has guest-starred in the series. The producers of the show had been trying for years to get Nimoy, who has largely retired from on-camera acting, to appear on the show.^[21]

Howard is hired to maintain Stephen Hawking's wheelchair while he is lecturing at Caltech. Howard plans to bring Sheldon along to meet his idol until Sheldon insults him again about his physics knowledge. After endless pleading, Howard agrees to give Stephen Hawking Sheldon’s latest paper on the Higgs boson, but only if Sheldon performs several tasks for him. Howard makes Sheldon clean his large collection of belt buckles, walk through the Caltech cafeteria in a French maid costume and do his laundry. Bernadette learns what Howard is doing, and tells him to stop until she remembers she was going to go dress shopping with Mrs. Wolowitz and suggests the last task for Sheldon is to go in her place. While shopping for the dresses, Sheldon is forced to go into the women's dressing room and squeeze Mrs. Wolowitz into the dress as it does not fit her. Before agreeing to give Sheldon's paper to Stephen Hawking, Howard asks Sheldon to compliment him once for his work. Sheldon replies that he has never said that Howard is bad at his job, only that his job is inconsequential. Howard looks past this and tells him that he gave Stephen Hawking his paper three days ago and that he wants to meet him. At his meeting, Professor Hawking tells Sheldon that the paper is excellent, though he mentions that Sheldon made a small arithmetic mistake on page two. Once Sheldon finds it and realizes he gave his idol a flawed paper, he faints in front of Hawking. Professor Hawking remarks, "Oh great, another fainter".

Recurring character: Carol Ann Susi as Mrs. Wolowitz
Guest star: Stephen Hawking as himself

The guys discuss Howard's bachelor party. Howard declines strippers as he promised Bernadette there wouldn't be any. At the party, everyone offers a toast. Sheldon tells jokes that fall flat but wishes Howard well. Leonard tells everyone he has had sex in the ocean and does crazy things. Stuart tells everyone how unhappy he is living in the back of his comic book store while Barry Kripke complains that there are no strippers. Raj finishes with stories about Howard losing his virginity to his second-cousin, having sex with a Sailor Moon girl at ComicCon and Leonard and Raj getting him a Jewish role-playing prostitute in Las Vegas. All the while, Wil is recording everything and uploads it to the internet. When Bernadette picks Howard and Raj up, she is mad at both of them after seeing the video. She wonders how she can marry a man that she doesn’t seem to know. When talking with Penny and Amy, she becomes upset at Penny since she knew about his past when she set them up sending her out of the room in tears. Howard shows up and gives Penny a message that he was sorry and the man Bernadette knows is who he is because of her which reduces Penny to tears. Bernadette hears him and tells him that the wedding is still on, though that she is still mad at him. They all end in a group hug which Amy finds exciting. Leonard whom Penny earlier had told that he doesn't do crazy things, shows up in the laundry and proclaims that they are going to have sex right then on the washing machine. Penny scoffs, and refuses, and says that he should help her with the laundry. Leonard replies, "Folding sheets in my underwear: still pretty crazy!"

Recurring characters: Kevin Sussman as Stuart Bloom, John Ross Bowie as Barry Kripke and Wil Wheaton as himself

Howard receives word from NASA that his mission to the International Space Station has been cancelled, due to the Soyuz rocket failing its pressure test. Despite the sympathy shown to him from the guys and Bernadette, Howard is secretly relieved, as he was starting to get scared of going into space anyway. However, NASA later calls and informs him that his launch has been rescheduled, and the launch date is the Friday before their wedding. Bernadette is relieved for Howard, but he uses every excuse he can think of not to go including going to see his prospective father-in-law. Bernadette’s father tells Howard that he did not think that he was the right man for his little girl until he heard about him going into space. Also he mentioned not to worry about the wedding deposit and that Bernadette can always find someone else if he doesn’t come back.

Meanwhile, Penny offers to take her "beta test" relationship with Leonard to the next level and takes him to bed, but it ends badly when Leonard proposes to Penny in the middle of sex. Later Penny sees Leonard in the hallway, kisses him and then gives him "No" to the marriage proposal, though informing him that they are still dating.

Elsewhere, Amy uses her neurobiological skills to increase Sheldon's feelings for her by making him happy. She starts off by playing Super Mario Bros. theme background music (reminding him of "the best 600 hours of [his] childhood") and serving spaghetti with little hot dogs (which his mother used to make) with Strawberry Quik, and later playing doctor "Star Trek style" (Amy dressed in Star Trek attire). Amy’s actions seem to work on Sheldon, who isn’t happy about it but makes no attempt to stop her.

Guest stars: Casey Sander as Mr. Rostenkowski, Karl T. Wright as Jimmy and Robert Clotworthy as Dave Roeger (voice)

A very nervous Howard Wolowitz and his two fellow astronauts, Dimitri Rezinov and Mike Massimino are in the Soyuz capsule, awaiting lift-off to the International Space Station. Fearing for his life, Howard begins to reflect on the last couple of days, revealing that he married Bernadette before he left.

After giving Bernadette a necklace with a star on it which he plans to take into space with him, she tells him that she wants them married before he takes off, and they decide to the city hall that afternoon to marry there, and have the reception when he gets back. Amy is devastated that her position as Maid of Honor has been reduced to nothing, but is allowed to wear the dress she bought to city hall. No wedding occurs because there are too many couples in front of them. Later at the Cheesecake Factory, Raj suggests they get married on the roof of Leonard, Sheldon and Penny's apartment building on Sunday morning, which will coincide with Google's satellite taking new photographs of their city of Pasadena, California. The five friends then get ordained as ministers over the internet in order to perform the marriage properly. Although the wedding ceremony is heavily improvised, and is constantly interrupted by Mrs. Wolowitz, as well as Leonard's needling Penny over her rejection of his marriage proposal, it is a success.

The episode ends with Howard being launched into orbit. Watching nervously, Bernadette takes Raj’s hand, Penny takes Leonard’s hand and a very surprised Amy has her hand taken by Sheldon who wishes Howard well with the words “Boldly go, Howard Wolowitz.”

Recurring characters: Carol Ann Susi as Mrs. Wolowitz
Guest stars: Mike Massimino as himself, Casey Sander as Mr. Rostenkowski and Pasha Lychnikoff as Dimitri Rezinov