"Come on a cracker"
An apocryphal game that was part of schoolyard legend when I was in junior high school. Supposedly there were groups of adolescents who would go out in the desert (this was in Las Vegas) with a box of Saltine crackers. They would form a seated circle and begin masturbating onto one of the crackers. The last one to achieve orgasm would then, according to the rules of the game, have to eat the cracker.
Many were accused of participating in this activity, but I never saw any concrete proof that anyone ever actually did such a thing. Given that pretty much anything sexual that you can imagine is probably happening somewhere, though, it seems likely that there is a round in progress even as you read this.