The Gravity co-stars were at a dinner party one night when notorious practical joker Clooney and another pal tricked her into jumping into the water.
She says, "I went to the bathroom and came out and there was George and someone else with just their pants on going, 'We're gonna go in the pool,' and I was like, 'Really?'. And so I held their hands and on the count of three... I jump, and they let go, and I go in the pool...
"The sad part was I wore this cute little lace dress that I paid a lot of money for, and as I got out (of the pool), it started disintegrating."
Bullock should have been weary of Clooney's actions - the Hollywood hunk is well-known for playing tricks on his co-stars on and off movie sets, so she made the actor call a truce while working on their new space disaster movie because the shoot was too tough for pranks.