The actor entertained guests by ripping off his clothes and smothering himself in whipped cream on stage at the event in Las Vegas, before getting up close with a similarly-naked overweight performer and a dwarf in Cyrus's VMAs teddy bear outfit.
We're not sure if these pictures are hot or disturbing, but they're certainly eye-catching!
The Endless Love star threw another birthday party at the Skybar in Los Angeles last week, and at one point, Pettyfer was pushed into a pool by his mates, emerging in an impossibly clingy shirt. It may be your birthday, Alex, but we're the ones celebrating!
And by the way, his mates are pretty easy on the eyes too!
Pettyfer recently signed on to play a gay action hero in the new movie from The Butler director Lee Daniels.
He is also reportedly being considered for a role in Star Wars: Episode VII.