Used in a variety of situations from greeting one another to interjecting with it, used then in times of questioning, to making bad East Coast impressions.
(Greeting)
Roberto: Aye who the fuck!
Joe: Oh shit! Hey man good to see you how's it been!
(Interjection)
Joe: Hey let's go shag your momma tonight
Roberto: Aye who the fuck are you!
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?"