IT'S A TRAP

From The LURKMORE Wiki

A meme based on the line by Admiral Ackbar in Star Wars: Return of the Jedi; started on Fark around 2002, and spread to the rest of the Web from there over a period of years before ending up on /b/. On 4chan, "IT'S A TRAP" took on a new meaning, being used in response to pictures of men who appear to be women. Degenerated into "IT'S A TARP", which is basically the same thing. Later gave rise to the term REVERSE TRAP, referring to a female cross-dresser.