A woman is in her doctor's office, and suddenly shouts out "Doctor, kiss
me".

The Doctor looks at her and says that it would be against his code of
ethics to kiss her.

About 20 minutes later the woman again shouts out "Doctor, please, kiss
me just once".

Again he refuses, apologetically, but says that as a doctor he simply
cannot kiss her. 

Finally another 15 minutes pass, and the woman pleads with the doctor
"Doctor, Doctor, please kiss me just once!!"

Look" he says, "I am sorry.  I just CANNOT kiss you.  In fact, I
probably shouldn't even be fucking you!"