Snap Backing The (ThE) (tHe) (a) (An) (A) (an( Comma (comma) (&) (,) The Ol(L)d D(d)usty Ass-w(W)iped Trail (A (The-An) Postal Code 10457-2219 On The Topic Of Zipper's Code)...
Person 1: Are you addicted to abscesses?
Person 2: Yes.
Person 1: Snap Backing The (ThE) (tHe) (a) (An) (A) (an( Comma (comma) (&) (,) The Ol(L)d D(d)usty Ass-w(W)iped Trail (A (The-An) Postal Code 10457-2219 On The Topic Of Zipper's Code)...
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.
FRIEND A: "Did you just take a stealthie of me?"
FRIEND B (turning phone around): "no I was just using snapchat's new filter, see?"