Doctor and Plumber-haha FUNNY

A pipe has jst burst in a Doctor's house. He calls a Plumber. The Plumber arrives, unpacks his tools quickly, does mysterious plumber-type things  & hands the Doctor a bill for $600. The Doctor exclaims, "This is ridiculous! I dont even make that much as a Doctor!!!". he waited him to finish & quietly said, " neither did I when I was a doctor"