George Clooney and Julia Roberts gatecrashed Gwen Stefani's Carpool Karaoke

James Corden's latest Carpool Karaoke started off like any other. He had Gwen Stefani gracing his passenger seat, singing classic tunes from across her almighty career (and FINALLY telling us how to sing that really fast bit about the refrigerator in The Sweet Escape.)

But then the car became unprecedentedly star-studded. They hit the HOV 4, a lane where you need four people in the car (it must be an LA thing...) and luckily, Corden knew a guy who knew a gal and soon the car was stuffed with A-list talent...