Hotel Suspicions

Riddle: A woman was in her hotel room when there was a knock on the door. She opened the door to see a man who she had never seen before. The man said, "Oh, I'm sorry ma'am, I thought this was my room." When he went to the elevator, the woman phoned security. What made her suspicious of the man?

Answer: You think you would knock on your own door? Source: https://riddles.com/index.php/5127

A woman was in her hotel room when there was a knock on the door. She opened the door to see a man who she had never seen before. The man said, "Oh, I'm sorry ma'am, I thought this was my room." When he went to the elevator, the woman phoned security. What made her suspicious of the man? — Hotel Suspicions by Phillip Cooper Riddle