Matt Damon already said "I Do," but is George Clooney next?

During an appearance on The Late Show With David Letterman Thursday, Damon, 39, let the talk show host in on a plan he and Brad Pitt hatched as a joke to get his longtime pal hitched while in Italy for the Venice Film Festival.

While speaking to reporters at the film fest, Pitt, 45, was asked when he'd wed partner Angelina Jolie. His cheeky response? When "George Clooney marries his boyfriend."

Things quickly got lost in translation with Italian journos and the joke went farther after Damon was approached for his reaction to Pitt's comment.

See adorable pics of Pitt and Jolie with their twin babies.

"So this Italian journalist comes in and goes, Matt, is it true what Brad say?" Damon, in a faux Italian accent, tells Letterman. "And I have no idea what he us talking about But of course, I go, 'Yeah,  it's true.' And he says, 'Do you mean George Clooney have a boyfriend?' And now I'm trying to keep a straight face and I go, 'Yeah, of course he's got a boyfriend. And he wants to legally marry him. We've been on him about this for years...' "

Clooney, 48, finally got wind of his pals' hyjinx Tuesday at a press conference carried on CNN when a gay Italian journalist asked for his hand in marriage.

Watch Clooney's reaction to the proposal here.

"I'm sure George is still laughing about that one," says Letterman.

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