You can start with a sudden and unexpected event like 'The elevator stopped, and a cold hand touched my shoulder.' Just focus on a quick, spooky moment.
The brevity. With just two sentences, they create a sense of mystery and unease. There's not enough space to fully explain what's going on, leaving a lot to the imagination.
They often rely on the unexpected. Like 'The painting on the wall changed. It showed my future death.' The sudden and strange event in the first sentence is then made even more disturbing by the second sentence. This makes the reader's mind race with questions and a feeling of dread.
One story could be about a haunted house. A girl entered an old, dilapidated house. As soon as she stepped in, she heard a strange whispering. In just 7 seconds, she saw a shadowy figure pass by. She tried to run but the door slammed shut. It was a terrifying experience.
The story of the abandoned asylum. In just 7 seconds, a visitor saw a patient's ghostly figure in a straitjacket running down the corridor. The asylum was known for its cruel treatments in the past and the spirits of the tortured patients still lingered.