George Clooney Talks Pranking Matt Damon Into Thinking He Was Gaining Weight

Matt Damon has his work cut out for him if he’s ever going to get pal and co-star George Clooney back for pranking him into thinking he was packing on the pounds.

Last year, while the stars were filming the upcoming “The Monuments Men,” George took aim at Matt’s waistline.

“Matt showed up [to set] saying, ‘Man, I want to lose 10 pounds while I’m here, get a trainer, workout,’” George, 52, told Access Hollywood’s Billy Bush and Kit Hoover on Friday.

PHOTOS: The Always Dapper Gentleman George Clooney

“I said, ‘Man, you look good to me.’ He was going home every weekend to see his family and I would have the wardrobe person just take in his wardrobe a quarter of an inch for two weeks,” George said of his prank.

And Matt kept what he thought was a growing waistline a secret.

“Who’s going to come out and say, ‘Hey, I’m getting fatter, these pants don’t fit me!’” the actor continued.

PHOTOS: Hot Shots Of Leading Man Matt Damon

But George never got around to telling his fellow Oscar winner about the prank.

“The worst part is, I forgot to tell him about the joke…he found out about it a week ago,” the “Gravity” star explained.

And how did Matt, 43, feel about George’s joke?

“It was brutal, it was brutal!” Matt told Billy and Kit “He knew I was angsting about it and he knew I wouldn’t say anything about it. He’d just go, ‘Why aren’t you losing a couple pounds? You said you were going to lose a couple pounds.”

“The Monuments Men” opens on February 7.

— Jesse Spero