Word of warning, I know this story sounds unbelievable, and frankly I have trouble with it myself. So you're within your rights to doubt it. I wouldn't hold it against you for thinking it's bullshit.
This happened years ago, when I was in college (I'm probably way older than a few of you). A friend of mine (let's call her A) had got her hands on an old Ouija from a garage sale. So, being dumb nineteen-year-olds, six of us get together for shits and giggles and use it one fine afternoon. Years later, I learned that six people is the absolute worst number for Ouija, but whatever.
So we're messing around, asking various questions, not getting much until something spells out SCREWLOOSE, which to this day I assume is the name of something we were talking to. Just for laughs, because we don't know any better, we ask it how much it really knows. Over a couple hours, Screwloose (again, only assuming this is a name) tells us personal secrets, stuff we hadn't shared with the other people holding the planchet. This freaks some people out, so they get up and leave (without saying goodbye). The rest of us laugh it off, get on with our lives.
About a week later, A's roommate C comes to my friend M and myself. C is worried about A- she's been skipping classes, ducking homework, staying up late to mess around with this Ouija. M and I go to talk to her, this good little Catholic girl, and she matter-of-factly tells us she's been talking to Screwloose. Again, we shrug it off, tell her she shouldn't be skipping class.
A few more days pass. C calls M, a little more freaked out. She's roommates with A in a college, remember, which means they share one bedroom. Lately, stuff has been moving around, C keeps hearing strange sounds and having nightmares. And the night before, C woke up to see some dark figure standing over A's bed.
We go to see A yet again, and we get a little freaked out ourselves. A had lost about ten pounds, had huge dark circles around her eyes, and kept denying there was any problem. Then there was physical evidence. Like I said, A was a Catholic, and was in the habit of taking off her rosary and dropping into a glass while she slept. We found that glass completely shattered and the rosary missing. The way the glass had shattered was weird, too- the round base was intact but the glass was spread out around it in a perfect circle, like it had exploded from the inside. Not really sure what to do at this point, I give A a lecture and take away her Ouija. I take it back to my own dorm and shove it under my bed, planning to figure out what to do with it in the morning.
The nightmares I had that night are far worse than anything I've had before or since. A tall woman in a red dress bursts into my room, climbs into my bed, attacks me, whispers things in my ears before she tears them off. I wake up in a cold sweat, arms and face covered in deep scratch marks. I assume I somehow scratched myself up in my sleep, because I don't want to think about the alternative. The following day, M and I drive the board out to the middle of nowhere and burn it. It's over, right?
Wrong. I keep having nightmares, so bad I can't sleep. I see a woman in a red dress out of the corner of my eyes every once in a while, but say nothing. Two years later, I compare notes with M, discover he had a similar problem at the same time, except he was seeing a man in some kind of hooded robe, like a monk's habit or one of those boxer's robes or something like that.
He didn't tell me until two years later, but one night M got jumped suddenly while walking home from the library alone. The way he tells it, for a second he was convinced he was struggling with a person in a robe, only to find out it was actually a trash bag blown by the wind. He tells me he must have been mistaken, it was never a robed person. I have trouble with this- I have been in dangerous situations with M and he's kept his cool. A tornado, a mugging, some drunks attacking us outside a bar- M had been fine with those things. He's not the type of guy who's going to freak out and assume a plastic bag blowing in the wind is someone coming after him. So he can try to convince himself all he wants, I'm going with his initial impression.
And worst of all, A has made herself a new Ouija out of cardboard. You ever known a drug addict, or someone with a serious drinking problem? That's how she was with this Ouija.
There's not really an end to this story, no climax. The semester ends, A transfers to a school in Kansas and we don't really talk anymore, C drops out. M and I don't really talk about what happened for a couple years. I don't really know how things ended up.
But I do still sometimes have nightmares about a woman in a red dress.
Anyways, sorry for the wall of text. Like I said, you're free to disbelieve this story, and if you think it's untrue I hope you at least got some entertainment out of it.