Megan Fox ‘Is Hilarious’ In ‘Knocked Up’ Spin-Off, Says Leslie Mann

We don’t know too much about Judd Apatow’s “Knocked Up” spin-off movie project, other than the fact that it centers around lovable/slightly dysfunctional couple Pete (Paul Rudd) and Debbie (Leslie Mann), a few years after the events that occur in the Katherine Heigl, Seth Rogen pregnancy comedy. Also, if we know one thing about Apatow comedies, it is more than likely that a slew of famous faces will appear in the film, be it in a supporting or cameo role.

Apatow has been cagey about revealing any more casting or cameo details, but one interesting addition that was actually announced back in March is Megan Fox, and although we don’t yet know who she plays in the film, star Leslie Mann assured us that she is a welcome addition to the cast.

“Megan Fox is so funny,” she told us Monday night at the Los Angeles premiere of “The Change-Up.” “She’s hilarious. You wouldn’t, I don’t know if other people [expect it], but I think she’s really funny, you’ll be pleasantly surprised.”

So who does she play in the film?

“I can’t say that part,” she said with a smile, backing up her husband’s comments earlier this year regarding spoilers.

“The rest is a secret because it doesn’t come out until 2012 and if you already knew what it was about for a year and a half, you wouldn’t even want to see it,” he told us. “There will be people who are really interesting in the movie,” he teased. “And some familiar people who are in the movie.”

Are you excited to see Megan Fox’s comedic chops? Tell us in the comments or on Twitter!