Back in high school, I saw some meme on 4chan right before bed that said something like "Spooky fact #666: If you wake up at 3:33am, it means someone is watching you". It even included some generic horror movie / demon face and I chuckled to myself because it was so silly and over the top.
Well that night, I randomly woke up, turned to face my clock, and saw it was exactly 3:33am. I was still half asleep but I remembered the meme I saw and thought to myself "How funny would it be if I turned over and saw someone watching me?" So I turned over, thinking I could put my silly fears to back to bed. Except, there was a shadowy figure standing in my open doorway. I was paralyzed with fear and accepted that I was going to be killed by a demon or ghost or whatever paranormal creature decided to fulfill the prophecy of "spooky fact #666" and just closed my eyes and went back to sleep.
I woke up in the morning without any further incidents and assumed it was just a nightmare caused by a dumb meme. I got out of bed and bumped into my mom in the kitchen, and I mentioned the nightmare I had last night about the demon. She laughed to herself and responded, "Oh that was me, I like to watch you sleep at night when I can't sleep." It's been over a decade and I still have waking nightmares sometimes where I think I see shadowy figures standing in my room.