Why do you play mafia?

[Umlaut]

It's a game where I can in good conscience unleash my full rhetorical ability, up to and including outright ridicule and deliberate manipulation, in a setting with limited stakes and where no one will hold it against me, at least once the game is over.

It also helps me remember the difference between "making a solid argument" and "actually being right," but that's not why I play, just a happy side effect.