The rules are simple.  Find an unsuspecting target and use your open hand to smack the target's testicles with the knuckles in a flicking motion. One point is awarded for each testicle that is amputated from your target.

Teenager Has Testicle Amputated After 'Tapping' Game

"It's just gotten way out of control," said Dr. Scott Wheeler, a urologist in Brainerd, Minn. who says he performs three to four surgeries a year on boys with ruptured testicles and other complications as a result of "sack tapping."

"All parents, you need to have this talk with your kids not to do it. It's lost its humor. It's not a game anymore. People get hurt," he added.