I did not have naked doctor exams as a kid, but had my first as a young teen when I had to get a physical for a summer job with the city. Went to the health department rather scared because of the many stories I'd heard about Doc S. So I showed up, and the nurse told me to undress down to underpants.
Doc came in and did all the "normal" tests, then sat in his wheeled office chair and closely watched me do several calisthenics (pushups, situps, bend over touch your toes, walk across the room and back) in my white briefs. It seemed we were finished after that, but my feelings of relief quickly vanished when Doc asked me to stand in front of him (he was seated with his desk behind him). I did so, and he began to quite thoroughly feel me up the front, back, and between the legs of my underpants. Without warning he slid my briefs down to my knees, and ordered me to take them off completely. I was now naked and embarrassed.
He pushed my thighs apart so I stood before him with legs spread fairly wide as he performed an aggressive hernia check, then much more feeling around. He ordered me to walk across the room again and back as he watched carefully. I was quite excited but don't recall getting hard - maybe just slightly. Then he asked me to turn around and do 5 or 6 slow toe touches as he sat behind me and observed my hairless butt crack and boy hole. When I finished he ordered me to face him again, legs wide apart so he could re-examine my very early pubescent penis and testicles much more. I felt more butterflys in my stomach, and got semi-firm before he completed his inspections. Though very embarrassed, I recall his hands being quite warm and comfortable on my genitalia.
He finally finished his examinations and told me to get dressed, watching me closely the entire time. I look back on that and wish I could have been the Doc with a nervous young teen to examine!