And gak rollercoasters. *hides in fear* But who in their right minds would give Joker a building permit for a carnival?
As "The Killing Joke" showed, if the guy with the green hair and fixed grin wants to use a carnival, no one would probably stop him, or be in any condition to ten minutes later. Or maybe the Joker just told them he wanted to tie his pretty little hostage up, and they wanted to see it too! :)