Doctor says: "One of several things could cause your symptoms."
Doctor means: "I haven't the foggiest idea what's wrong with you."

Doctor says: "Are you certain you haven't had this before?"
Doctor means: "Because now you've got it again."

Doctor says: "I'd like to run that last test over."
Doctor means: "The lab lost your sample."

Doctor says: "This prescription has a few side effects."
Doctor means: "You may experience sudden hair growth on your palms."

Doctor says: "Your insurance should cover most of this."
Doctor means: "You'll have to sell your house to cover the rest."