Unexplained Horrors of Reddit

What's the most terrifying, unexplained event you've ever witnessed? User 'ShadowWhisperer' writes:

I woke up to a faint scratching sound from inside my wall. It slowly grew

louder, like something trying to claw its way out. Another user,

'GhostlyGaze', recounts: My friend and I saw a shadowy figure.

It was standing at the end of a long, dark hallway in an abandoned house.

And 'MidnightCaller' shares: My phone rang at 3 AM. No caller ID. I answered,

and all I heard was a child's faint, distorted laughter.