Pics or it didn't happen. Used in forums when a user makes a ridiculousclaim nobody thinks they can back up. Often used when a member claims to be female, due to the high likelyhood of this being untrue.
when you're holding up your phone and making faces at it, as though you are taking a selfie, but you're really taking a picture of the person across from you or the wall or anything else that seems interesting but you don't want to be caught dead taking a picture of.
This action is often made more convincing by wiggling the eyebrows or opening the mouth, to pretend you're trying to get a Snapchat filter to work.