If the push-up video didn't convince you Justin Bieber's a hard mofo, this should do the trick -- the singer showing off his badass tats in jail ... so police could take photos of them.
The Miami Beach PD just released the pics -- presumably snapped to keep a record of Bieber's identifying marks -- and they're GANGSTA AF.
Not really ... but it's hilarious that Bieber obviously thinks so.
We can't really decide on our favorite -- it's a toss-up between the weeping Jesus face and the inexplicable Native American head (the singer once claimed he was "part Indian").
The real shocker is how Bieber can stay standing with two gold chains around his neck.