I feel like people complaining about the tattoos on the joker looking "stupid" sort of miss the point.
Like seriously, have you actually thought about the Joker objectively?
He paints his face white, has green fucking hair, and wears lipstick. The dude laughs maniacally while he commits mass murder. I think having "Damaged" tattoo on his head is exactly the short of stupid asinine shit that the Joker would do. And he probably tattooed the "hahahahas" just to troll internet forum readers.
He doesn't paint his face white nor did he dye his hair green though. That's what he actually looks like.