A Ouija Board is a serious hazard. (From Hasbro!)
Laugh if you wish, but please avoid them.
It certainly can be. Players closing their eyes and "concentrating" can reach a sort of communal suggestivity similar to hypnosis, without the guidance of a responsible hypnotist. That usually turns out to be no more than a silly game but sometimes the insecure or otherwise vulnerable can be sent places they really don't want to be. It's mostly good fun but sometimes it's not.