ZAC EFRON's most famous role to date was an all-singing, all-dancing teenage basketball star in High School Musical.

But from the look of his new trailer, that's all set to change.

The heartthrob strips completely NAKED in his new movie That Awkward Moment and lies horizontally on the toilet after taking too much Viagra.

And the actor is one wrong move away from going full-frontal as he balance precariously on the bath edge.

In the raunchy red-band trailer, the muscly 25-year-old is also seen talking on the phone topless and lying in bed naked after a sex scene with Imogen Poots' character.

Zac plays Jason, who makes a pact with his friends to remain single after one of the trio is dumped– but, of course, he then meets the girl of his dreams.

The trailer is chock-full of fart gags and sex jokes– think a more grown up American Pie- but the film is sure to attract the ladies with the promise of seeing Zac's naked body on the big screen.

After making his name as a squeaky clean Disney star, Zac started to shed his good guy image after dropping a condom on the red carpet and dating High School Musical co-star Vanessa Hudgens– she of the naked picture fame.

The hottie admitted to recently finishing a stint in rehab for cocaine addiction, and it looks like the sober star is back on the dating scene. After being spotted with his arms around his Hairspray co-star Brittany Snow at a concert, Zac was also seen staring adoringly at the beautiful Lily Collins after a cinema date.

We don't know who we're more jealous of– Lily, or Imogen getting to film these saucy scenes.

That Awkward Moment is due to be released on January 31st. Can we book tickets yet?