The act of masturbating (wanking) whilst in a party with your mates, that are in earshot of your moaning through the headset.
I came back and put on my headset and was greeted with vigorous sexual noises coming from a member (Kellah) in the party. Kellah is a blooming partywanker!
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?"