Willow

Brad Pitt will have audiences laughing out loud as a knucklehead fitness employee in Burn After Reading, but what makes PEOPLE's two-time Sexiest Man Alive chuckle in real life?

"My kids," Pitt, 44, told PEOPLE at the Toronto International Film Festival gala screening Friday for his new Coen Brothers comedy also starring George Clooney.

Speaking of his kids with Angelina Jolie, newest additions, eight-week-old twins, Knox and Vivienne, are great, he added.

"Everyone is healthy," said Pitt. "No sleep though."

He added to reporters: "Sleep is something you long for, but it's alright. We'll get it."

Despite the lack of shut eye, costar and Oscar winner Tilda Swinton advises Pitt not to worry. As a mother of twins herself – 11-year-old daughter Honor Byrne and son Xavier Byrne – she tells him: "It gets easier! And it's true."

And what kind of dad does she think her movie star friend is? "He's fantastic," said Swinton. Costar John Malkovich chimed in: "He was very doting with his daughter during shooting on a couple of days I was there. He's very much a present parent."

Pitt and Jolie have six kids total contributing to the giggles: Maddox, 7, Pax, 4, Zahara, 3, and Shiloh, 2.

Source People