Why was this guy trying so hard to be a jerk?

I met a guy at a party this weekend, and he was kind of disrespectfully joking around while sober, and when he got drunk he was all over me, which was fine, but he kept saying over and over, "I'm an asshole, I'm an asshole", etc. He said it in the same I'm-trying-to-be-funny tone of voice that he used while being a rude comedian earlier. I'm not sure if he was apologetic or trying to be explanatory, but I'm pretty sure he was trying hard to be a jerk. Why would he do that? What is he trying to hide?