When someone (usually male) takes a big dump in a toilet, then proceeds to shoot at the piece of poop with a strong stream of pee. Typically, the goal is to break the poop into two pieces. This can most easily be accomplished if the poop is in log form.
Jason (on the phone): "Hey I gotta hang up. I need to go in the bathroom for a round of poop and shoot."
Platoon daddy: “hey fuckface, where is SSG Jody?”
Sgt o’cheese: “I heard him say that he was going to the port-a-shitter to have a poop and shoot. Private Cuck’s wife sent him nudes.”
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?"