An invisible man is here to see you
Nurse: Doctor, there is an invisible man in your waiting room.

Doctor: Tell him I can't see him now. Next.

A man was walking in the street when he heard a voice...
A man was walking in the street when he heard a voice: "Stop! Stand still! If you take one more step, a brick will fall down on your head and kill you."The man stopped and a big brick fell right in front of him. The man was astonished. He went on, and after awhile he was going to cross the road. Once again the voice shouted: "Stop! Stand still! If you take one more step a car will run over you and you will die."The man did as he was instructed, just as a car came careening around the corner, barely missing him."Where are you?" the man asked. "Who are you?""I am your guardian angel," the voice answered."Oh yeah?" the man asked..."And where were you when I got married?"