Its his twisted mind… Joker has something called super sanity. No, its not a typo, if you're thinking he has super INsanity. Joker can basically see and understand things in a different perspective to all the other comic characters. read more
Joker can basically see and understand things in a different perspective to all the other comic characters. Its a worse form of insanity. So, the reason why joker laughs so much is because he finds it funny how everyone is scared or serious, when he (in some cases) knows he is a comic book character. read more