[SERIOUS] People of Reddit, what was the creepiest thing you experienced that you thought was paranormal, but was actually much scarier when you found out what really caused it?

About 7 years ago, my family rented a one story house. It was originally one bigger house that was split off into two, and there was another family that lived in the other part that we didn't really talk with. During the night, I would hear what sounded like knocks above the ceiling, but any entrance to the small "crawlspace" between the ceiling and the roof was patched up when the house was divided. For a while, I thought there was a ghost who lived in the "attic", and I would have trouble going to sleep without a light on. After we moved out, I heard through the grapevine that the neighbor's kid was caught spying on the new people that moved in. Turns out that he had broken a hole in the ceiling of his closet to get into the crawlspace and had been looking through holes that he had bored in the ceiling overlooking the other part of the house. The noises I heard was him moving around on him arms and knees up there.

/r/AskReddit Thread