A woman was in her hotel room when suddenly there’s a knock on the door.
She opened the door to see a man whom she had never seen before. He said, “I’m sorry, I have made a mistake, I thought this was my room.” He then went down the corridor and in the elevator. The woman went back into her room and phoned security.
Why was the woman so suspicious?
Because the woman suspected that if he really thought it was his room then he wouldn’t have knocked at the door.
The man might have an intention to break in, in order to steal something, if no one was in the room. He knocked to make sure that no one was in there.