To get the Tragic Clown to appear on your sims' lot, you must first buy the "Tragic Clown" Painting and hang it somewhere in the house. Once you've done this, make your sim family have an average mood of negative twenty. After that, the Tragic Clown should appear. Be careful, though, as he'll likely make the average family mood drop even lower. If you want him to appear right away, there's an NPC summoner that has the option to summon the Tragic Clown that you can get here: www.gs.gaming-fusion.net .
If it gets too annoying then you can just pick up the phone and call the clown catchers. But they take away your tragic clown painting. : (
