My son's 15th birthday is today. All he wanted was money. That's not very fun, so my wife decided to spice it up a bit.
She made him play beer pong (actually water) for it. $5 a ball. 18 shots. If he made them all he'd get a $10 bonus for an even $100.
It was hilarious watching him sweat it out. He ended up winning $70, which is what we were going to give him anyway. Perfect outcome.