Why So Serious? Arkham City Has A Big-Head Mode
Big-head modes are a classic gag in games, adding a few extra laughs to titles like GoldenEye and NBA Jam. Don't think that Batman is above having a little fun with a big ol' noggin, even though he likes to play up his Mr. Serious persona. Rocksteady has hidden the mode in Batman: Arkham City, and you can check it out here.
The guys at Rooster Teeth have put together a nice demonstration of the cheat, which is activated by pulling both triggers on a controller and spinning the analog sticks. It works with all characters and skins, such as the Batman Beyond skin pictured above. As you can imagine, it's a laff riot.