Back in the late 50s, it was common to have children's tonsils removed if you had frequent ear aches. This required hospitalization and I got mine out with my older sister at the same time and we shared the same room.
You had to have your temperature taken rectally. My 10 year old sister complained and wanted an oral. the nurse said it had to be rectally because some kids swallowed the glass thermometers and that would not be good. I was watching from the other bed and her fear scared me. The nurse told her to be a big girl and show how brave you are. Then, the nurse scooped me up and sat me on my sisters bed. She had her turn over and her johnny fell away from her buttocks.
I may have only been 4 years old but I liked this view. The nurse took a thermometer out of a Vaseline filled vial and it had a nice glob of Vaseline on it. I had never seen this done before and was fascinated to observe this. I know my sister saw our mother take my rectal temp when I was younger as she told me about her helping by holding my legs up to keep from kicking. She saw me get suppositories too.
Anyway, the nurse let me watch her spread my sisters buttocks wide open and I saw my first female asshole. Darker than her surrounding skin, slightly open, not tightly closed. and then, with a slow motion, the nurse inserted the red, Vaseline covered end into her rectum. It slid in easily and sis moaned a little bit and as nurse pressed her palm over the end pressing down, sis said it hurt and "too deep". Nurse moved her hand and the thermometer started to rise out of her anus a little. After a few minutes, nurse removed the thermometer and wiped it on a tissue. It had poop on it and nurse commented that would need to be taken care of. Sis quickly rolled over and closed the johnny.
My love of the image of a female asshole was set for life. More true stories on becoming an anal addict to come.