A Weeabo is a term for a person who imitates Japanese culture (sometimes to the annoyance of others). Another term for this would be Otaku or Wapanese. The term origionally came from a comic in The Perry Bible Fellowship as the name of a game. This game invovled those who say "Weeaboo" getting paddled by everybody in the room. It came to refer to a Wapanese when the mod at 4chan made the word filter change Wapanese to Weeaboo.
(1) http://pbfcomics.com/?cid=PBF071-Weeaboo.gif (2) http://wiki.iiichan.net/index.php?title=4chan_Glossary
