Comic book writer Justin Jordan noted on social media that any Joker with the patience to sit still for a tattoo just doesn't feel like The Joker. The number of jokes about the "damaged" on his head is pretty impressive.
So...what's the deal with the tattoos? We have (or have heard) a few different ideas that seemed worth mentioning.
Somehow we've been quoted as "confirming" this theory, and I'm not sure where that came from.
There's been a lot of talk, though, about the fact that the "legacy" nature of the tattoos and the idea that most or all of them come from various comic book stories and concepts, coupled with the timing coinciding with The Joker's 75th anniversary, could mean that the tattoos won't appear in the film at all.
At least one fan has taken that to the next level and, as you can see at right, has set out to prove that the tattoos are inserted by computers, and not part of the makeup on Leto's actual body.
They're symbolic, and meant to represent the character's history
This could be the same as, but isn't necessarily mutually inclusive of, the previous point.
In most cases, the people who suspect that the tattoos won't appear in the final film, assume that the reason they were there in the first place is that they were winks and nods to various iterations of The Joker throughout the character's history.
Those elements are definitely and obviously there, but whether that means the tattoos won't be a part of his look in the film is something else entirely. It could be that this apparent maniac has tattoos in the film that wink and nod to his character history in the comics.
Being self-aware in this way would be a weird way to go for The Joker, but it could tie to the notion currently being played with in the comics that The Joker is an ancient force for anarchy and that he sees everything he's doing as some elaborate chess game.
Could these be less a style choice and more something done out of boredom? Going back to Jordan's comment about Joker's restlessness, years in jail could plausibly be even more dull than sitting back for a tattoo. Most of them don't look like they were done jailhouse style, though...but that hasn't stopped a LOT of people from speculating about it, so it seemed worth at least mentioning.
Some are self-applied
Why are they so fixated on identity? Well, some people have been speculating that the tattoos are self-applied. Basically a variation on the jailhouse tattoo idea, the notion is that at least some of the "hahahahaha" stuff and potentially the "damaged" tattoo, the "J" and the like, are something Joker could have put on himself while in solitary confinement.
Of course, this presupposes that someone would give The Joker, of all people, something sharp enough to use to make tattoos. Which seems unlikely.
He isn't the real Joker
This one is totally far-out, and deserves to be credited, but I saw it somewhere on a comment thread and I have no idea where.
Yesterday, someone on social media noted that this didn't look like The Joker as much as it did somebody who was obsessed with The Joker. With Harley already out there, the notion of The Joker having imitators/impersonators isn't totally out of line...even if it's a colossally long shot.