Notorious prankster George Clooney called a "truce" with his Gravity co-star Sandra Bullock because the sci-fi movie shoot was too tough for practical jokes. The Ocean's Eleven star is well known for playing pranks on his co-stars on and off movie sets, but Bullock has revealed the actor didn't have time to catch her out during the gruelling Gravity shoot. Speaking to the audience during a panel discussion at the Comic-Con event in California, Bullock said, "There was a truce... This film was so hard - pranks had no place. We had no downtime. How are you going to prank someone who's hanging from a scaffolding where 12 wires are rigged up all day? We had a truce from the very get-go because that just wasn't the appropriate place to prank someone." Clooney's previous targets have included Evan Rachel Wood, who was secretly taped dancing to a Justin Bieber track while working with the actor on The Ides of March, and Up In The Air writer/director Jason Reitman, who flew into a panic after the star hid his beloved Golden Globes trophy.