The Clown is the most important crewmember. A Clown's jobs are to entertain, amuse and, to an extent, annoy. Unlike the reserved and silent Mime, the Clown operates from a place of obnoxiousness; each Clown is standard-issued with throwable custard pies, slippy banana skins, an irritating horn, and squeaky shoes.
Any good Clown knows that annoyance is only a path to amusement. The amount that you're going to be able to get away with is directly proportional to how funny it is. Slipping on a banana peel is only funny once, so be creative. Tell jokes, scale your pranks up, involve the Mime (as confederate or target), steal the Captain's shoes. The only limit to Clowning is your imagination (and Security (and the admins)).