The Amityville Horror
Demons, a ceiling that oozes green slime, hell in a basement and a creepy voice yelling "Get out!" That all sounds like Hollywood hooey. Except the Lutz family claimed it had really happened to them in their new house. Problem was, they couldn't quite keep their stories straight. Didn't stop them from making a pile of money off the movies. And the sequels. Which at least everyone admitted were made up.