Alright, so there is this abandoned "insane asylum" near my hometown that was on a massive property. It had been abandoned in the 80s and every once in a while me and my friends would hear stories of people going and exploring the place. It was absolutely massive, consisting of at least 15 buildings, a basketball court, an electric factory (I think) and a church. All of these buildings are connected by a set of underground tunnels which are absolutely pitch black except for a little bit of natural light that is let in at random intervals. Oh, and I forgot to mention there is a graveyard on the property with just numbered graves… so yeah, textbook scary insane asylum.
One summer day me and two of my friends decide to go check the place out. The cops don’t want people going in there for safety reasons, so we were all camoed out and snuck in through a hole that someone cut in the perimeter fence. We made our way to the main set of buildings and found a window that wasn’t sealed shut with plywood.
Now the interesting thing here is that once you find a way into a building and use the tunnels to get to another one, you have no guarantee that there will be a way out of the building you end up in. Unless you memorize your path or leave breadcrumbs or something, you have to find a new way out. We were in what I think was the main office building and after checking out the morgue (which had CSI style body tray things and everything), we headed into the tunnels to check out what was down there.
The entire time we were in the tunnels, we all felt on edge and creeped out, which is to be expected I guess. They’re extremely damp and cold, and again, pitch black. We went up into another building or two, a dormitory and something else, and didn’t find anything too interesting (relatively speaking). Eventually, when we were back in the tunnels, we saw a passageway that had a bunch of do not enter tape and plastic blocking it off. People had clearly already been in there, as it had been cut at some point.
Naturally, we went down that tunnel. At this point we were walking single file, and somehow I got the worst of the deal and ended up in the back (alway the first one to die in horror movies). The tunnel went straight about 15 yards and then turned right. At the corner of that right angle turn, there was a grate, which I assumed was for maintenance access. It had a little crawl space behind it, and the grate was open.
For some reason, I decide to close the grate, which made an extremely loud grinding sound. This was the first loud sound me and my friends had made the whole time we were there. I’m somewhat convinced that this is what woke up the thing we were about to see…
At the end of the tunnel there was two doors, one was wide open, leading to an empty concrete room, the other led to a staircase into another dormitory building. My friend in the front opened the door and started up the stairs, the kid behind him followed, and I brought up the rear. As I turned to move through the doorway I instinctively looked over my shoulder with my flashlight as I had done many times before (checking for murderers, obviously).
Thats when I saw him/it. There was a perfect silhouette of a man standing about 4 feet in front of me, just out of arms reach. He seemed to be wearing a towel around his neck or something like that. I immediately yelled “WHAT THE FUCK?!”, turned around and shoulder checked my friend in front of me to sprint up the stairs.
The worst part is that when he turned around at my exclamation, his face went pale and I knew he saw it too. All three of us sprinted up the stairs in absolute sheer fucking panic, not knowing if we were being chased or whatever generally happens when you see stuff like that.
Once we made it upstairs we knew we were done exploring for the day and wanted to GTFO as fast as possible. To our dismay, there was no way out of that dormitory that we could find… meaning we had to go back the way we came. Back into the tunnels.
Funnily enough, nothing happened on the way out, but we were all scared shitless nonetheless.
For the record, I still don't believe in ghosts or anything like that. I saw what I saw but I think the combination of being so tense and expecting something to happen made me hypersensitive to anything out of the ordinary.
My best non-supernatural theory as to what I saw goes like this: When my buddy in front opened the door, some sort of draft was created when the warm air upstairs met the cool, damp air downstairs. Some form of condensation or something created a temporary mist cloud in front of me and my mind turned it into a ghost.
TL;DR - Ghost man thing scared the crap out of me and my friends in an abandoned insane asylum...