I know you've all been waiting for it. Check out What a Fart, a farting game with a convincing core mechanic. You play the role of a gassy chap waiting at a bus stop. Gas builds up in your gut that must needs be released, but take care not to offend social convention and disturb another fellow at the bus stop. Wait until cars pass by and take the opportunity to mask the sound of your flatus with their engine noise. Don't build up too much gas or you'll explode. Longer farts mean more points!

The game itself is in Korean but you'll get the idea. It would be nice if the difficulty scaled up as you played for longer, but it's an, erm, charmer as is.

(thanks to Nico)