You can get a bunch of "Hello, my name is" stickers, write different names on them, put them all over a shirt and be an identity crisis.
You could be white trash -- just punch some holes in a trashbag and wear it -- stuff with newspaper and staple fake trash to the outside.
Wear a nice suit/tie and a sign around your neck that says "I'm sorry" and go as a formal apology.
Wear a suit with a red tie and print up a couple of soul contracts to be Devil's Advocate.
Get a tinfoil hat and be a UFO conspiracist.
Wear pajamas and when someone asks what you are, say "sleepy".