When I was younger, maybe 11 or so, I used to go to a church that rented a school Sunday mornings and Wednesday nights. The service would be in the cafeteria, while the kids were sent off to some of the first floor classrooms. The second floor was completely off-limits.
Well, being a young kid obviously I wanted to go to the second floor so one Wednesday night me and a couple of friends sneak up and walk around. The school was huge, and all the lights were off, so we were walking in dark, empty hallways. We kept thinking we heard steps and breathing, but we pretended not to be scared because, again, young kids.
We were scared out of our minds.
After a few minutes of walking around, we turn a corner and see this door with something yellow covering it. We get closer and see it has safety tape all around it.
"CAUTION — DO NOT ENTER — CAUTION"
We looked at each other and ran away. Sunday morning we decide to go again. We walk around for maybe 10 minutes but we can't find any door like that. Our parents notice we're missing, and when they figure out where we were, we get in trouble and aren't allowed up there anymore.
Eventually we forget about it. That is, until we're bored one Wednesday night while the adults were in the service, and we decide to explore upstairs again. This time we're all bravery and making loud noises to show we were older and not intimidated by a dark hallway. That is, until we turn a corner and see, yup, a door with yellow tape covering it.
We all shut up immediately. I'm about to piss myself. Somehow we get the courage to walk up to the door and peek into the window. We see a dark shape move and suddenly, these big red eyes are looking straight at us. We scream and run away, losing our heads.
A few weeks later I go by myself on a Sunday morning and find the door. I look inside and I see it's the Principal's office, and there's a computer monitor right around where the red eyes were. We probably looked into the office of the principal, who thought safety tape on his door was funny, on a night after having fallen asleep at his desk and his weird screensaver coming on or something.
I never told my friends about it. I figured it might make life more interesting for them to think they saw some kind of demon monster at their church when they were young.