[overdrivetg]

A fun way to play with people who won't believe you is to say OK then, let's play 10 games @ $10/game:

Get 3 cards and pick one to be the prize. Your mathematically-challenged partner gets to put them down each time.

You pick a card, they remove one of the other cards and then you always switch.

I made like $50 from someone this way one time =)

I'm not totally heartless - I took him to lunch on me afterwards to lessen the blow ;-)

If you really want to drill the point home, offer to keep playing more & more batches of 10 until they've had enough...