Nurse and Patient
Classic fantasy. Ever seen how many sexy nurse outfits are available for purchase?
1. For many young boys the first time a person sees their penis post puberty is when they get a checkup at the doctor's office. Think about it. Often this quick check up is performed by a male doctor, but in the fantasy the nurse/doctor is a female who is interested in more than just physical health.
2. Similar to a young boy, often the first time another person sees a woman's vagina is at the gynecologist. While occasionally a man, obviously nothing sexual happens during these visits. Well, in this fantasy visit to the doctor, the patient gets more than just a basic checkup.