House of the Dead is the only movie I ever walked out of and demanded my money back.

Also so many comedy sequels.

Super Troopers 2, Dumb and Dumberer, Dumb and Dumber 2 (which actually made Dumb and Dumberer look good by comparison; at least the Bob Sagat part was hilarious and still remains quotable), Anchorman 2, etc. I haven't seen the new Happy Gilmore sequel yet, but I have heard it actually is decent.