Apparent misspelling of the word 'insane'.
Originates from the "How is babby formed" Flash cartoon of 2 cavemen discussing how babies are formed.
The cartoon got it's 'text' from a Yahoo Question.
Synonyms for instain
On this page, you will find 30 slang terms related to instain. Some of the top words include: funnay, intarweb, smrat, fucknutty, mispell, and 25 more.