There is a line that is all over internet attributed as being said by the Joker:
Smile because it confuses people. Smile because it's easier than explaining what's killing you inside.
But I can't remember from Batman: The Dark Knight when Joker character might have said this... All posters from internet contain Heath Ledger's Joker with the quote.
Is it said by him at all? If so then in which scene? Or is it from a past Batman movie? Or from the comics? Can anybody recall anything?