The contrast. For example, when you start with something normal like 'My neighbor always gives me strange looks' and then follow with 'Today I found out he was looking at the ghost behind me'. The normal - to - spooky shift makes it effective.
The old cemetery was silent. A man went there at midnight. He felt a chill in the air. Then he saw a ghostly figure floating above a grave. He ran away as fast as he could.