Uddering is a sexual position/act involving 2 partners. It occurs when a male is naked on all fours and the other partner masterbates him into a bucket which is directly under him. The partner then drinks the ejaculation from the bucket.
Friend: So what did you and Johnget up to last night?
Girl: Oh we tried Uddering. It didn't taste very nice...
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?"