The X Factor and American Idol judge appeared as himself in the horror spoof, in a sequence about an amateur rapping contest.
Speaking to Entertainment Weekly, he said: "I'll never forget going to that premiere and dying in my seat when the movie came on.
"I've never felt so embarrassed in my life. Lesson learned. Don't believe that you're good at other things. I might be okay as a judge, but I'm a lousy actor."
Cowell was recently voted one of the magazine's top 15 entertainers of the decade.