Rules are: has to be something that happened or a horror story that you made up and are made to be serious.
I'll start...
This is a true story that happened a while back.
Back in the Ukrain I lived with my grand parents on the 5th out of 10 floors. There was a scary floor, we called in "floor -1" it Leeds to underground passages like a maze, it's grey moldy walls covered in web, and the dim light bulbs that hung by a thread of wire ready to fall. The tunnels had 2 ways out, one way in. We started a stupid and dangerous game of race, who ever gets out 1st wins. I was the smallest one in the group... I can't imagin how damp, and dark it was in there... Before the blackout happened. My so called friends made it out 1st, I was last... In the middle all of the lights on the block turned off and I let out a scream that just jumped off the walls and never made it to the ears outside. 30 minute passed and I was feeling my way out on the wet rocky floor. I found a light that was so dim I could barely see 5 feet, afcours it was powered by a generator, the light was in a cross road postion like an X, I sat in the middle. An hour passed like what had seemed a week in the pits of cold hell, I was so terified that my brain began playing tricks on me, like what had seemed I heard faint wispering in the concret walls! Followed by that I heard constant foot steps getting closer. Next thing I remember that I woke up in my warm bead with a feaver, they said 5 hours passed, but for me it was a leason of a life time.
Afcours it's not true :D, I would be in a hospital then!
But the tunnels are true, they are used to store things like canned food or old toys for the winter