An okay replacement for a Cum sock if the laundry hasn't been done. Although may lead in to some confusion.
P1: Hey sorry i was really thirsty so i drunk your milk.
P2: What milk?
P1: You know, the one on the desk.
P2: Oh my god.
P1: What do you mean?
P2: That was my Cum Mug.
P1: WTF!
P2: This is what happens when you don't do the laundry Steve!
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.