A contact high is a psychological phenomenon that occurs in otherwise sober people and animals who come into contact with someone who is under the influence of drugs. It involves a supposed transfer of the physiological state of intoxication. A glossary of drug users' language from the 1970s describes the term as "a psychogenic 'trip' without taking drugs by being close to somebody while he or she is on drugs. The term is often incorrectly used to describe the high obtained by inhaling the smoke of other marijuana smokers."
In Alexander Shulgin's PiHKAL book under the 2C-I entry, a notable reaction is observed in a participant who takes a placebo, existing in an environment with other people who are under the drug's influence. The participant wrote that he had "absorbed the ambience of the folks who had actually imbibed the material."