A woman waved to a man in a taxi. She got into the taxi and told the taxi driver where to take her. He nodded to her and drove. The woman talked a lot and that annoyed the taxi driver. The taxi driver said," Ma'am, I can't hear what you are saying! I am as deaf as a post!" The woman stopped talking for the rest of the ride. Once she got out of the taxi, she realized he was lying. How did she know?
There are two ways she figured out: 1. He would have had to hear her to know she was talking as he was focusing on driving. 2. He would not have heard her directions if he was deaf and wouldn't have nodded in response as a way to confirm he got the directions.