It was 3 o'clock in the morning. John was sleeping when he heard a glass breaking noise, downstairs in the kitchen.
Frightened he woke up and shouted "Who's there?"
He decided to go down, just to find out. He turned on the lights and everything was in perfect condition. On returning to the room he inadvertently bumped into a glass. The glass fell over.
Silence. From above a familiar voice shouts, "Who's there?"