Zac Explains... Sack Tapping?

And now for your educational moment of the day: Here is Zac Efron, explaining what "sack tapping" is! And yes — "sack tapping" is more or less what it sounds like, except it's slightly more violent. Basically, it's punching somebody in the balls, but you've got to watch Efron explaining it firsthand.

Efron appeared on The Graham Norton show alongside his Neighbors star Seth Rogen to chat about the movie, which in the U.K is titled Bad Neighbours. Since the movie is about a young dad (Rogen) who lives next to a heavily partying fraternity in which Efron is a brother, Norton inquired if Efron had any experience with fraternity-esque traditions. Efron didn't go to college, but he is into on-set brotherhood, so he, indeed, is familiar with this little testosterone-driven — and, in bad situations, testosterone-destroying — game.

Efron asserts that he isn't very good at the game, but Norton and his informative cards say otherwise...

You can watch 26 minutes of this episode of the talk show below — and it's well worth it, as it features a great chat between Norton, Efron, Rogen, and Matt LeBlanc, too. The informative moment on sack-tapping is particularly ball-busting (HAHA, couldn't help myself there) and starts at 14:25...and of course you want to hear Zac Efron talk about the very masculine game that is testicle-punching.