True Story

I was standing on the Metro on the way home, and it was very crowded, and an old woman standing an inch away from me pointed down and said, "Did you drop a screw?" I looked down and saw a brass bolt about two inches long lying by my right foot. Standing nearby was a man who rides my train at the same time I do every day, and with whom I have chatted on several occasions. He laughed and said, "She thinks you have a screw loose." I said, "No, sir, I have performed a self diagnostic and all of my mechanical parts are functioning normally."