Not look bothered in an argument?

Well, theres a guy in my last block cl everyday, and he's a real you-know-what. He always listens to my conversations with OTHER people, so he could come up with some insult against me. Its pretty funny watching him squirm after I throw a really good insult at him, but sometimes my anger takes control and I almost beat him senseless. I know he enjoys watching me get mad, so whats the best way to look like it didn't affect me, to make him squirm more?