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 doctor is complaining to a mechanic
A doctor is talking to a car mechanic, "Your fee is several times more per hour then we get paid for medical care."

"Yeah, but you see, doc, you have always the same model, it hasn't changed since Adam; but we have to keep up to date with new models coming every month."