Well, there's a story where some college students used a Ouija board in their dorm room. Things went wrong when the planchette started spelling out threats. They were told that they would all have bad luck. And soon after, they started failing their exams, getting into arguments with each other, and having all sorts of problems. They blamed it on the Ouija board experience.
I heard a story about a couple who used a Ouija board during a vacation in a spooky old cabin. They asked if there were any spirits present, and the answer was yes. Then the spirit started to communicate in a really menacing way, saying things like 'you're not welcome here'. The couple got so scared that they left the cabin in the middle of the night. The whole thing made them believe that there are some forces that should not be messed with when it comes to Ouija boards.