Talk about putting it in the vault.

It turns out Matt Damon has known about George and Amal's twins for months. “We were working together last fall and he came up to me on set and took me aside and told me and I was so happy for him,” Damon told the Today show.

That film is likely the Clooney-directed criminal comedy, Suburbicon, from screenwriters Joel and Ethan Coen.

Clooney, in his excitement, spilled the beans a bit earlier than conventional standards would dictate. “I said, ‘How are along are you?’ And he said ‘eight weeks!’ And I said, ‘Don’t say anything!’ ” Damon joked. “He didn’t know the 12-week rule. You’re supposed to wait!”

How much do the two A-list friends trust each other? "(Clooney) never even said, 'Don't tell anybody,'" Damon told Entertainment Tonight. "He told me (and) I'm sure he knew I'd tell my wife (Luciana Barroso). My wife wrote to Amal immediately, 'Congratulations.'"

The twins, which are due in June, according to The Talk's Julie Chen, are in good hands, says Damon, who called Amal "spectacular" and George "so loving."

But Damon, who has four daughters with his wife: Alexia, 24, Isabella, 14, Gia, 12, and Stella, 10, says his prankster-friendly Ocean's Eleven co-star better prepare himself.

"I've never had twins. He has it coming," he told ET. "It's going to be a huge challenge, I mean, one baby cries, wakes the other up. It's going to be on in that household." But, Damon added, "he doesn't sleep a lot anyway. He'll be all right.

"I'm serious, he's got a hell of a work ethic."