WATCH: John Travolta joins the Foo Fighters on stage for epic ‘Grease’ rendition

During their headlining set at the Welcome to Rockville festival, the Foo Fighters thought they'd mix things up a bit by playing a revved up version of the 'Grease' classic 'You’re the One that I Want' - and it sounded AWESOME!

But what made their performance even better?

The arrival of none other than Danny Zuko himself... John Travolta.

While his appearance was lightning-quick, the crowd went wild for the 64-year-old - who was apparently in town filming 'Moose', a new thriller directed by Limp Bizkit’s Fred Durst.

Travolta’s surprise appearance marks the latest in a long line of unexpected guests at Foo Fighters shows, including ’80s icon Rick Astley and Billy Idol.