Witherspoon says, "We were doing a scene and Mark said, 'I can't stand you, I want you to get out.' Then he jumped out of the window.
"We were on a second-storey platform up in the air, and he's got the stuntman to put out the mattresses and not tell us.
"We all screamed, then he popped up and jumped back in the window.
"It was so funny. He was always cracking up and doing silly things."