rectum roulette
a game you play if you enjoy giving anal sex where you're never quite sure what the state of the arse is in, therefore it is a roulette of rectums.
normal-tight-normal-loose-tight-goatse, you lose :)
Rectum roulette
The risky game of chance that occurs when you attempt to squeak out a fart that could either be harmless gas or liquify into a shart.
"Phil, last night I spun the wheel in my white linen pants and lost at rectum roulette. It was a disaster."