Cheryl's Bum-Flash Shock

Cheryl ColeGirls Aloud went back to school...

And talked about, well, bottoms, at the St Trinian's world premiere.

Lucky us nattered to Cheryl Cole and Nicola Roberts at the star-studded world event, held in London's Leicester Square.

The girls have a cameo in the movie, and recorded songs for the soundtrack.

Nattering about any embarrassing moments on set, looking at Nicola, Cheryl told Sky Showbiz: "Your bum was on show at one point. The stylist had us in really, well, you couldn't even call it a skirt, it was more like a belt...

"And Nicola's was particularly short. At one point I looked over in a take and I actually seen a bit of a cheek, a bit of a bum cheek."

Nicola RobertsSo, what were the girls like at school?

Cheryl reckons: "Chatterboxes, I was the class clown. They'd call our your name on the class register and I'd say 'Mickey Mouse' and stupid things."

Go and see Girls Aloud in their sparkly outfits, and other stars, at the St Trinian's world premiere.