LL Cool J was caught out at the theatre in Los Angeles recently when he dashed onstage to stop a prop from falling - only to discover the accident was part of the production.
The rapper/actor was in the audience for James Whitmore, Jr.'s Better Days when he jumped to action in an effort to protect one of the stars.
He says, "They had this scene at the end of the play where the wall is coming down and the shelf turns into this heavenly thing. I thought the bookshelf was really falling.
"I jumped up... and ran on the stage real crazy... and then I realised it wasn't falling. It was transforming. It was part of the play.
"The girl onstage, the actress, was, like, kneeling down in front of me, and she was just looking at me like, 'You're ruining my performance...' I never felt so crazy in my life... You can't be cool all the time."