For 2 - ~8 players.
Whoever farts first says “service!” and “serves” the ball and they are now the hitter. Whenever someone else farts they say “return” the ball is “returned” and they become the new hitter. If you fart when you’re the hitter, say “score” and you get a point.
Work in teams of two. If either person in a team farts, the whole team becomes the hitting team. The whole team can score by farting while being the hitting team.