I first begin by making jokes to try to lighten the mood, when some ass insults one of the fish at my table. (The player insulting the fish is almost always a bad player himself, but slightly better than the one he's insulting)

If the attack continues, I begin attacking the obnoxious player myself, defending the fish, etc, in an attempt to get the jerk to fight with me rather than the fish.

Someone in this thread brought up a good suggestion, though. Next time I think I'll try getting the jerk to attack me by making obvious stupid silly statements, like "He was right to call to the river with pocket 2's, I always win with pocket 2's, they're the luckiest hand" and so on.