Doctor Roy had just finished a marathon sex session with one of
his patients. He was resting afterwards and was feeling a bit guilty
because he thought it wasn't really ethical to screw one of his
patients.
However, a little voice in his head said "Lots of other doctors
have sex with their patients so its not like you're the first...". This
made Dr. Roy feel a little bit better until still another voice in his
head said, "... but they probably weren't veterinarians".