He dares wear short-shorts!

Zac Efron played his edgiest, most outlandish character yet -- for Halloween, that is!

The High School Musical hunk, now 24, partied on Halloween with sisters and 78Violet bandmates Aly and AJ Michalka, who tweeted a pic of Efron's unexpected getup.

Mimicking Lieutenant Jim Dangle, flamboyant cop from Reno 911, Efron donned short-shorts, a '70s-porn style moustache, sunglasses.

"Love our friends xo," the Michalka sisters (in sexy costumes themselves) wrote below the caption.

Tell Us: Do you like Zac's look?