What are the scariest short two - sentence horror stories?

Another really scary one could be 'My phone rang at 3 am. The caller ID said it was me.' It plays on the idea of the self being something other or unknown, and calls at that time are always spooky.

Well, the one where 'I woke up in a coffin. As I screamed, I realized I was buried six feet under.' is quite terrifying. Just the thought of being trapped alive underground is a nightmare.

Well, there's 'My daughter won't stop crying and screaming in the middle of the night. I visited her grave yesterday.' Also, 'I heard a noise from the basement. The power has been out for days so it couldn't be the furnace.'

I woke up to the sound of scratching at my window. When I opened my eyes, a shadowy figure was peering in.

The sudden and unexpected events. For example, a character thinking they are alone and then suddenly seeing a shadowy figure right behind them.

The sudden appearance of unknown entities. For example, a figure suddenly showing up in a supposedly empty room.

I think 'I heard a child crying in the basement. But I live alone.' is quite terrifying. The idea of a crying child in a place where no child should be, especially when you live alone, plays on our fears of the unknown and the supernatural. It makes you wonder what could be down there, and the thought that it's not a normal, explainable situation is very frightening.

I think 'The clock stopped at midnight. Then I heard footsteps.' is quite scary. It gives this feeling of something ominous starting right at a spooky time.

I saw a figure at the end of the hall. As I blinked, it vanished, leaving only a chill.

In some, it's the sudden appearance or disappearance. For example, 'She was walking in the empty hallway. A figure emerged from the wall and vanished.' The unexpected emergence and then quick vanishing is really scary.