When one guy seemingly at random punches another guy in the chest, knocking the air out of him. This is done back and forth between the two males as a game. Each incident is increasingly surprising for the victim.
Guy 1: -sitting on the couch, watching T.V.-
Guy 2: -creeps up behind couch, with stealth-
Guy 1: -goes to change the channel...-
Guy 2: -attacks- "CHEST!"
Guy 1: -falls over, without air-