Another alternative - have a Jester as a specialist hireling for castles and leave it at that. If for some insane reason a player wants to play a medieval standup comic, it sounds like something based on Etiquette and some sort of Perform skill really.
Elevating insults and chorus lines to the level of a character class - we've all done it, written them up and so on but only tiny numbers of player bother to play them usually and then - often not well.
Plus if any class can perform as a Jester using skills - or a Jongleur or Mummer for that matter - makes picking on a Jester a lot more risky - could be a Magic-User, Cleric or Fighter under the bells.
Creating game materials? Monsters, spells, classes, adventures? This is the place!