One of the best things you can do is this:
Every time you hit a great shot don't say anything. Just look at him, smile, and walk away.
What are the rules about this? Is he allowed to jabber at you during your whole pre-shot routine and only has to shut up once you address the ball? Or is he only allowed to trash talk on the walk up to the ball/tee? The 2nd I feel I could learn to tune out. The 1st would make me want to start a fight.