A friend of mine told me this story about his sister, a veterinarian, who had to visit the doctor. The doctor asked her all the usual questions, about symptoms, how long had they been occurring, etc., when she interrupted him:
"Hey look, I'm a vet--I don't need to ask my patients these kind of questions: I can tell what's wrong just by looking. Why can't you?"
The doctor nodded, looked her up and down, wrote out a prescription, and handed it to her, with the words: "There you are. Of course, if that doesn't work, we'll have to have you put down."