Just keep it simple and creepy. Start with a normal situation and end with a terrifying twist in the second sentence.
First, create a suspenseful setup in the first sentence. Then, shock the reader with a horrifying reveal in the second. Make the contrast sharp and unexpected.
Well, think of a common place or object in the first sentence. In the second, introduce a terrifying element related to it. For example, 'I opened the closet. A ghostly hand reached out.'
I woke up in the middle of the night. A shadowy figure was standing at the foot of my bed, staring at me with empty eyes.
The man entered the dark forest. Out of nowhere, a howl pierced the air and he saw pairs of glowing eyes closing in on him.
Well, start with a creepy concept. Then, make each sentence build the tension and shock. Keep it short and sharp to give that quick scare!
Well, start with a spooky idea. For the first sentence, describe something normal but hint at something off. Then, in the second sentence, reveal the horror. It's all about surprise and tension.
You can start with creating a creepy setting. Like, 'The abandoned hospital was silent. A cold draft blew through the empty halls.' Or build tension with, 'I opened the closet door. A shadow lunged at me.'
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.
First, come up with a terrifying idea. Then, in the first sentence, set the stage and hint at the horror. In the second sentence, reveal the full horror in a sudden and unexpected way.
I woke up in the middle of the night. A shadowy figure was standing at the foot of my bed, its eyes glowing red.
Story 1: I woke up to a cold hand on my face. When I turned on the light, no one was there.
Some might be based on real experiences or fears, but many are fictional creations for entertainment.