My story's a little weird, so bare with me.
I've been best friends with Elisa* for a few years now, and I'm always over at her house. However, her house has never really liked me. She's told me of strange things that have happened to her there; weird nightmares, feelings of uneasiness, lights going on and off, strange hallucinations, etc. At least she thought they were hallucinations, until I felt and saw things, too.
She'd often see a hand appearing from behind doors, holding and waving a little cloth with strange writing on it. It freaked her out terribly, so I, being naive at the time, brought over a Ouija board and we played in her basement. We contacted very mean spirits who supposedly lived in her house, and after that things got worse over there. That night I was sleeping on a mattress on her floor while she was on her bed beside me. The fan went on all of a sudden, and me being an extremely light sleeper and a naturally cold person, I woke up. We often joke about the fan because she's always putting it on full blast because she's naturally hot, and I end up wearing my winter jacket in her room.
She promised not to turn it on in the middle of the night, so when I woke up I said something like, "Elisa, you promised to leave it off, I'm freezing!" She didn't answer, so I got up and turned it off, and as I walked back to the bed I noticed I could see my breath as I exhaled. Now I don't think the fan could have gotten it that cold in there, but I went back to sleep nevertheless.
I woke up to her scream that morning, sat up in bed, asking what was wrong, still half asleep. "Look at your arm!" she shouted. I looked down at the underside of my left forearm to see that it was crusted with blood, and had been cut with a knife or razor blade or something. I ran to wash it in the bathroom, to uncover the word "BITCH" had been carved in jagged letters. It hurt, but I definitely didn't feel anything that night and, like I said, I wake up at the slightest thing. I still have the scar to prove it, although most people figure it was self inflicted.
All I can say is I really can't explain what's gone on in that house, but I think it was a big mistake to use that stupid board, which probably enflamed the problem.
*Names have been changed.