Mr. LAW and I actually do this all the time. Not the "i'll get you off if you do this" variety of bet, but I'm a huge footbal fanatic, so we bet on games. It's a big turn on to be out at a sports bar or somewhere public where the game is on, get into a discussion about the winner and end it all with a "wanna bet?" (complete with cocked eyebrow and nasty sexy grin of course)