A doctor 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 soits not like you're the first..."

This made the doctor feel a little bit better until still another voice in his head said, "...but they probably weren't veterinarians"