@Lily1991 ,
Perhaps one day you will experience having your 98.6F or 37C checked rectally. You might find it rather pleasant and arousing!
As for the diaper position, no thanks. Rather on my stomach or over a caretaker’s lap which I’ve been.
While in the hospital a number of years ago for a clinical trial which I got paid to participate in and made aware that rectal temperatures were to be taken( which many volunteers on hearing opted out) , there were two nurses assigned to me. One was a Filipina, the other a Latina, both in their mid or late 20s and very attractive. They were quite adept at taking rectal temperatures too. Part of their duties in which as I soon realized as they did the procedure, were well trained.
They did various procedures including my vitals and I eagerly awaited their arrival ( not both together for vitals but for other things, yes)) for that.
Entering the room whichever one it was, would go to the cabinet next to my bed, take the thermometer out of the drawer, hold it up, read it, shake it down then lubricate it. it was time for my temperature taking and they would say something to the effect, “Time for your bottom to be checked” or “You know where I need to put this! Turn over, now!”
They had me roll over on my stomach, I had my pajama bottoms and my briefs pulled down, my cheeks spread and soon a glass mercury thermometer well placed up my rectum for 3 or so minutes. The thermometer was taken away and replaced with another sterilized one for the next check.
These days I have a friend who is a nurse and comes by. Her visits include rectal temperature takings and enemas ( coffee) for liver detox. I’ve also been given butt injections as well.