We used to party a lot at a friends apartment,one of our rules was when someone got up to go get a beer if anyone else yelled beer you had to get them a beer,well one night I got up to get a beer and a friend promptly yelled BEER! Being slightly intoxicated I grabbed him a beer out of the fridge and turned around and threw it at him nailing him upside the head nearly laying him out cold! Needless to say a no throwing beer rule followed shortly after that episode.
I bet that has happened with 80 percent of beer drinking friends. I bounced one off my buddies head when he wasn't looking (neither was I) i just tossed it in his direction.. cause of that same "beer" rule..