George Clooney and Matt Damon
01/17/2014 at 02:00 PM EST
is a gifted actor and director. But he's also a gifted prankster, as Matt Damon
learned yet again while filming The Monuments Men
"He took in my wardrobe by an eighth of an inch, every other day," Damon, 43, said Thursday at a press junket for the film
at the Four Seasons Hotel in Los Angeles. "[He] had the wardrobe department do that because he knew that I was trying to lose weight."
Instead, thanks to the wardrobe treachery, Damon thought he was gaining weight – which baffled him, given the hours he was logging at the gym.
"This was a job where I would go back to New York, where I was living with my family, and I would come back [to film in Europe] for two weeks," Damon said, as Clooney, 52, made no effort to stifle a laugh. "And then I'd go back to New York, and every time I came back my pants were tighter, and I was like, 'Ugh, this is weird. I've been going to the gym!' "
Yet Damon seems to have taken the prank in stride, as he was quick to compliment Clooney on his cinematic talents – as well as his good looks.
"George is obscenely talented as a director, I have to say," Damon said. "It can be a little annoying being his pal because it's kind of like God said, 'Maybe this time I'll just give one of them everything. Let's make him handsome, and as he gets older he'll even look better!' "
The Monuments Men
, a World War II-era comedy-drama co-written and directed by Clooney, opens Feb. 7.