I really like sandman's suggestion with the food and not letting him have any of it.
I guess its if he acts like a child, then treat him like one.

I also like the dime one. But instead of expecting him to put a dime in a jar, do it yourself. Then show him how many times he has insulted or 'made a joke' at you.

Just out of interest, how is he if and when you 'joke' at him? I wonder if he's the sort who can dish it out, and not take it.. Good luck. Prob with people like that, they never seem to think they're doing wrong. And even if you do manage to get through to them, it doesnt take long before it slowly creeps back in. At least that's what I have found. :-(