To lighten the mood while filming Babel, Brad says he was a joker on the set

Though Brad Pitt has been involved in some serious causes lately, the 42-year old actor showed a different kind of charity on the set of Babel, taking one for the team and giving himself a wedgie to lighten the mood.

In order to relieve some of the “frenetic anxiety” on the Moroccan set of his upcoming drama, he yanked up his pants to give himself a wedgie, stuck out his rear and waddled around like a duck, PEOPLE’s two-time Sexiest Man Alive tells Entertainment Weekly in its Oct. 30 issue.

“Throughout the movie, I’d walk around like this,” he said, demonstrating for the magazine.

The laughs Pitt provided were sorely needed during the location filming, where temperatures reached near 112 degrees and there was only one indoor toilet. “You’ve gotta find things to make you laugh during the shoot,” he said. “Cate (Blanchett) called it the Hungry Bum. When your bum’s so hungry it’s trying to eat your pants.”

Pitt and Blanchett play a husband and wife whose vacation in the African desert is marred by tragedy in the Alejéndro Gonzalez Inérritu-directed epic, which opens Friday.

“What I liked most (about the script) was this idea that we’re all the same, and it’s our lack of understanding and lack of communication that gets in the way,” said Pitt, who has three children with Angelina Jolie.

“Our kids come from different parts of the world, and it’s the perfect example of, if we didn’t have these perceived differences we wouldn’t be defined by geography,” he said, referring to Maddox, 5, from Cambodia, and Zahara, 1, from Ethiopia.