Zac Efron Goes Balls Out On The Set Of The Townies

Literally!

Zac Efron showed off his um, impressive physique in a pair of tight sweatpants on the set of The Townies in Los Angeles on Wednesday, and we're not sure if that's a sock in there or if he's Jon Hamm-ing it up, but WOW!

The movie is about "a frat boy whose behavior affects a local neighbor's family life," and it also stars Dave Franco (yum!), Christopher Mintz-Plasse (loves him!) and Seth Rogen (for good measure).

We don't even NEED to see a trailer ... after all the photos we've seen of Zac so far, we know we wanna see this on the big screen! Emphasis on big...