Silly superstition. I'll also mention for archives: ideomotor response, cold reading, confirmation bias: there are a number of fun games to experiment with these and it involves nothing supernatural. A fun game involving both suggestion and ideomotor response is a friend holding down one's arms when trying to lift them up for a minute, then releasing them, with the arms left low and free, while the person who was holding them down now encourages them to lift up by themselves. After the binding sensation, there is a reverse sensation that the arms want to lift up by themselves, a suggestive effect that amplifies the encouragement of the partner claiming to be able to lift them by magic and encouraging it with hand gestures, etc. If it works well, the arms can be expected to lift only a little by themselves, then to unconsciously be lifted a little more by suggestion. In Ouija it's a bit similar where an initial impression of a pull is encouraged by further unconscious movement, but it can also be conscious, especially if one of the participants actually intends to influence the outcome, tricking the other. But it "works" even without that, without of course having anything to do with spirits or accurately predicting the future.
If it really worked for practical purposes, other than for entertainment or money scams, just like for remote viewing claims, there'd really be wide programs using it effectively, something we only see in fiction...
Since it's closely related I'll add more about "hypnotism": a trick is for instance to tell someone to place their hands in a posture where some fingers are difficult to move, then claiming that they are unable to move those fingers because of the hypnotist suggestion. For some people that works and is scary, then it may actually be possible for them to really believe that they're unable, or compelled to move in some simple ways by suggestion. Helping for public shows is the fact that some in the audience are glad to play the game and participate even if they don't feel any "mysterious effect", lastly it's even possible for one or some participants to actually be part of the show. The latter even happens with entertaining troups visiting some evangelist churches for blessing shows...