If someone on a forum website starts a thread or makes any kind of questionable claim, someone will probably reply to the post saying "Pics or Fake". As in, "post pics to prove that you are telling the truth, otherwise you are lying". %90 of the time this does not provoke the intended outcome, and goes relatively unnoticed by the OP.
Original post: "Seriously, one time I ran into Tina Fey at a bar in New York."

Reply: "Pics or Fake."
by Vidableek October 22, 2008
When you scroll down your twitter timeline and see a very attractive person's "twit pic" and you click on their profile to get a better look at them, to come to find that they are not as "Attractive" as they looked from your timeline.
Boy 1 (on twitter): Oh wow she's kinda cute.
Boy 2: Yeah she looks halfway decent.
Boy 1 *clicks on profile*: Twit pic fake out.
by Skillett1121 July 10, 2012