Take a movie, change a element, decision or whatever to 'ruin' the movie.
Louis Creed: "What if I bury my son in the Pet Semetery?"
Jud Crandall: "We did that once. Back in the 40's. We had to burn the house to get rid of the monster that come out of the ground." "Uyah... don't forget how my ah dog and your cat became evil!"
Louis Creed "You're right. I won't do it then. Better to lose my son than have him come back as a monster."