"Is there a doctor on this plane?"
"I happen to be a doctor."
"Oh thank goodness, we have a patient going into cardiac arrest."
"Oh no, you see, I have a doctorate...in evil. And I have just taken away precious seconds you could have used to save your patient! Mwa ha ha ha ha ha!"
"Do you at least know CPR?"
"Oh, I learned it when I was an innocent youth, long ago. But really, do you expect me to help anyone? Think of my reputation!"
"But CPR is kind of evil. You wind up breaking someone's ribs if you do it right."
"Ooh, you make an excellent point! Very well. Where is this patient -- I mean victim."