Skinny Batmen with cardboard masks or muscular Jokers wearing underwear over their pants? You can actually create both those and a bunch of other types of characters in Gotham City Imposters; the game lets you customize your characters. A new trailer from Gamescom touches upon this:
Gotham City Imposters is still a ways off. The game won’t see digital release until 2012. In the mean time, maybe this older, funnier trailer will give you an idea of what it’s about.