My mom was my pediatrician and all of her nurses knew I got rectal temperatures just like the other kids (until 7 years old) in mom's practice.
Mom had a playroom set up for me (the exam room right next to the nurses desk) before I started first grade because it was easier to take me to work with her than to drop me with a babysitter every day. She also wanted to spend as much time with me as she could. I am the baby of our family. Her last child.
I remember lots of times that I would be sick with a cold, playing in my playroom and one of the nurses would come in, open the cabinet and take out the rectal thermometer (the only one in the cabinet) and a jar of Vaseline and say “I need to take your temperature” or “Your mom wants me to take your temperature.” There was still a full exam room cabinet in my playroom.
I had a single twin bed for naps (the examination table had been removed) so some of the nurses would lay me on my bed , pull my pants down at take my temperature there.
If one of the exam rooms next door or across the hall were not being used some would pick me up, carry me there and lay me on my stomach on the exam table and take it there.
Most of the time they just sat down in the chair in my playroom, pulled my pants down and put me over their lap.
On several occasions one old nurse called me to the nurse's desk, put me across her lap and took my temperature while she answered the phone and worked on charts.
When you grow up around a clinic like I did, it seemed like getting a thermometer in my butt was just part of my world.