Not so much the epitome of the Joker, but something that tickles me nonetheless: the hand sanitizer. What kills me about it is that there is no one around, so he isn't playing for an audience. It's such a quirky thing to do, and if I ever thought the Joker was saner than he was playing it, that little moment really just said that he really is off his rocker to some extent.
 And, of course, the fact that he is wearing a nurses uniform. That never stops being funny. I'm amazed that they were able to pull stuff like that off in this movie and have it hit in just the right way, but they did.