Double Donkey Blumpkin
A double donkey blumpkin is a sexual act wherein two men sit on toilets facing each other, and recieve fellatio as they evacuate their bowls. Both men should climax simultaneously, and at the moment of climax punch their partner in the occipital lobe as hard as possible.
Rex, Jan, Jill and I had a Double Donkey Blumpkin party last night... it was a mess, there's shit everywhere.