Originally Posted by Darkhors
I'm not condoning cheating to win, but this is a great way to stop the cheating altogether. When he "obviously" calls an in ball out and there's no changing his mind, on the next point as soon as his ball hits the court, you call it out, grab the ball and move to the other side of the court to serve. He'll undoubtedly say something to you and then you can say, "if you're going to call my in balls out, then I'm going to do the same so we're playing on even ground". That should shut him up for the remainder of the match.
Some people are just so delusional that it doesn't matter what you do they're going to cheat just because. At that point, just pick up and leave as it's not worth your time.
You should try to get a lead if you can and then call every shot he hits out.