I've only lost 1 bet and I haven't made another on a sporting event since 1994. I had to buy my boyfriend dinner before a school dance when Arkansas beat North Carolina (or Duke, I can't remember which) in the NCAA Basketball Championship. I didn't really care who won the game, but his parents were both Razorbacks and my dad live in NC at the time, so it seemed like an appropriate bet.
At 15 I guess losing money was better than embarrassment. Now I'd take some minor embarrassment to lose of money any day.