Cameron Diaz gets a bum deal on the red carpet

This hilarious picture proves that we just don’t know what goes on ‘behind’ the scenes of a movie.

This snapshot of Leslie Mann, Cameron Diaz and Kate Upton at the London premiere of The Other Woman shows how close the girls got while filming.

As the actresses posed for a group shot, Leslie – who is married to Judd Apatow – decided to have a little bit of fun and grabbed her co-star Cameron’s leather-clad bum.

The Knocked Up actress couldn’t resist a squeeze, but we’re just sorry we can’t see Cameron’s reaction at that exact moment.

Sports Illustrated cover girl Kate Upton let slip that Leslie was very handy during the shooting of the movie, but wondered why she didn’t pay the same attention to co-star Nicki Minaj’s backside.

“I’m surprised you didn’t give her a little butt grab because you [Leslie] were pinching Cameron and my butt the whole time,” said Kate.