I know a lady who was simply invited by a guest to try ouija boards. She did it out of curiousity. The guest asked for a board (they used a dish) and wrote alphabets and some words like yes and no on the back of it. They all gathered and then a young man's spirit supposedly came and answered their questions mostly in a humorous way.
  Among those gathering around that board were two brothers and a cousin who after some months told others that it was they who were faking that young man's soul. And that they were moving the objects from one word to another just for fun and for teasing!
  Now in this case, there was no spirit, neither human nor demonic. Just a prank. Is it possible that some danger could come nevertheless?

During the prank a demon or more than one could have taken contol of the board.

Or the pranksters may have been tempted  to try conjuring for real rather than just playing a prank.

People have become posessed through use of oiija boards.

Any form of playing with a ouija board would be tempting God, and acting like we are a match for the Devil --- which we aren't.

Playing with them in any way is very dangerous and to be avoided at all costs.