Niles: I can't drink anything that's too hot. I have a toothache.
Roz: Oh. You been to the dentist?
Niles: Yes. He said the tooth is perfectly healthy but I still have this throbbing pain. I think I may have to go to the doctor.
Roz: Oh, it's probably just a sinus infection. Have you had a cold lately?
Niles: Couple of weeks ago, yes, but I'm over it.
Roz: That's probably what it is, a sinus infection. Happens to me all the time.
Niles: In all likelihood, I'm sure you're right. Thank you.
Roz: Of course I'm right. What else could it be?
Niles: Actually a toothache can be referred pain from something else.
Roz: "Referred pain."
Niles: That's right. For example, if I had a heart condition, I might not have pain in my chest, I might have pain in my tooth. You see, referred pain. So while you're probably right about the sinus infection, let's not discount the one in ten thousand chance that it might be something more serious.