Now who's crazy?

As I made my way back to my office after lunch, I observed a man who appeared to be talking to himself rather loudly while sitting on a bench. Being a hospital in the city, it's not completely out of the ordinary for slightly crazy people to hang around in the lobbies. A nurse, observing the same behavior I had, approached the man and asked if he needed to be helped.

The man looked at her slightly confused. Then he took the nearly invisible earpiece out of his ear and said, "Sorry, I'm on the phone. Could you repeat that?" The nurse sheepishly mumbled "Nevermind" and went on her way.