The guy is levitating the cards. The girl is trying not to spit her beer out while laughing at the guy, because his penis is sticking out of his fly. The girl with the torn stockings is spitting out what came out of his penis, moments before the other girl entered the room.
Of coarse the beer is the reason he was able to get a BJ from torn stockings in the first place, and also why he's about to get some from laughing girl too.