I do not currently plan to make a Jester class, and had posted on a thread asking a question "What would a Jester do that a Bard wouldn't do?"
While watching a movie last night, I got an idea.
In the movie, there was this guy, who had a briefcase, and in the briefcase was five million dollars in cash. This guy was obviously some sort of Rogue or thug or other serious criminal element type. But he encountered Harold, the protagonist of the film, and hilarity broke out, despites the attempt of everybody in the movie to make things follow a logical outcome that favored their own interests.
So, my idea, is that the Jester would be a character who makes hilarity happen. If a guy has a case with 5,000 gold pieces, it would just so happen that someone else would bring in an identical case, filled with women's underwear. And of course, who knows who gets whose case.
This makes a Jester a lot different from a Bard specializing in comedy. And it could be an interesting class to play, if anybody ever specs it up.