The actor was driving through Hollywood when he caught site of his face on a huge poster and braked suddenly to get a good look.
The driver behind rammed into him and when the two men stepped out to exchange insurance details the other motorist quickly realised he had hit the car of a star.
"I was so surprised I slammed on the brake and someone rear-ended me," he tells U.K. chat show host Graham Norton. "The other guy got out of the car unhurt but looked at me and followed my gaze and suddenly he developed severe back pain. I thought, 'I've made it and now he's going to take it all!' "