His personality is hard to pin down. People say that the Joker is into sadistic torture, but I really believe he's far more into mind games.
This was one of my favorite quotes of the movie, mostly because I know I would totally fall for that line. If he offered to let me know what my friends said in their dying moments, I would go over there and mess up that painted face of his. No matter how much I like him. I would try to, anyway.