Time to start randomly cup checking him in public... And not gently. Or, stuff your pants and watch the expression on his face when he gets a unexpected handful. Lol

I had an ex who would constantly grab my butt in public. He'd do it every few minutes. I kept asking him to stop. A good slap in the face worked....for about five minutes. Guys who don't respect you don't deserve you. Make him your ex if he doesn't stop. That'll make him realize you were serious.

Pretty sure I would break up with a guy over that, also. Maybe not the first time, but, if I had just spent a few minutes explaining to him why it was wrong and then he tried again, despite everything I'd just explained, yeah. I would end it right there. It's called being mature and having respect for each other, and for yourself. Gosh, what the hell is wrong with people today?!

Uhm...wizard's sleeve ? LMFAOLMFO!! xD

If that had been me, I would have punched him the first time he did it. Betcha he wouldn't pull that again.

My ex girlfriend used to do this. Lol .. So I would wait until we were in the middle of doing something serious, grab her boob and walk off. Lol

Not just inappropriate but also illegal.

And you're still dating the Douche bag???

Punch him when he does it

Your boyfriend isn't a douchebag like most people suggest it sounds more like to me that he doesn't understand social norms and is oblivious of the world around him - Sounds to me like he has a screw loose somewhere and at the very least may be mildly autistic.