First, Jared Leto looks absolutely incredible as The Joker. Especially the eyes. The hair, the skin, the lips, all spot on.
As for the tattoos, etc? It's a JOKE. Have people seriously not figured this out yet?
The Joker is taking the piss.
Think about it. He's IN PRISON in this movie. He is NOT your typical criminal. Therefore, he is "pretending" to be just that. A low level thug. He's essentially "playing a role" for kicks. The tattoos are all prison things, tailored to The Joker, in an ironic sense. We've heard that he will be "lifting weights", etc. Think about it. This is a character who constantly adapts and reinvents himself...why would he do any less in prison?
The "damaged" tattoo...that's going to be his way into Harley Quinn's heart most likely.
The giant smile on his arm? Pretty clever stuff, I think, a nice representation of his enormous grin.
Assuming this is how he will actually look, of course.
I love that people are so pissed off. That's likely exactly what the filmmakers wanted.
I love it.