What's the worst movie you have ever seen (and actually walked out of a theatre!)?

I hated that movie too.But the only time I've ever walked out of a movie was Star Wars The Phantom Menace because the theatre put the movie on without the sound track for 20 minutes by mistake then couldn't or wouldn't put it back to the start.I stood up in front of everybody and asked to speak to the manager and demanded my money back.He said ok and everyone walked out behind me!