Hope you enjoyed your coffee! Anyway, I'm like you in that as an adult, my temperature if I can get it taken rectally, is my preference.
I do it and request it because I believe it is the most accurate measurement, and I prefer the glass mercury thermometer. The "vintage", thin glass 4 or 4 1/2" glass numbered rod from 94F - 106/8F, etched with the word RECTAL ,the very distinct pear shaped bulb, and it has to remain in place a minimum of three minutes, sometimes depending on who is taking my temperature, longer, or depending on other variables, it might well be more than three minutes. NOTE: I have had digital & Electronic probes too.
It brings me back to my years when it was a common practice at home by my mother, and I remember the numerous times I had it taken rectally by the doctor for house calls or mostly during my hospital stays. The glass mercury thermometer.
Usually other than mom, it was done by nurses (female).
I've had it taken many times in role play and I have also had it taken prior to colonics /enemas at facilities and occasionally when on my stomach in my white cotton briefs on a massage table when the therapist removes them for the massage, then places the instrument (which I ask her to do-some will, some won't) in my rectum and massages me. That's one of those more than three minute readings.
The anticipation of it is/ was very exciting, especially as I got older, and could appreciate it as an adult. Yes, it is in my opinion the most accurate method, ergo...that's good enough for me!
There was and is an erotic titillating side to this "time honored" "gold standard". For some "loathed" ! And I can respect and appreciate that too.
I think my most memorable and I always think back to that, was when I was about 21/22 -not sure, where what I did not realize, lay dormant in me, but came back with a very powerful effect when I had my temperature taken rectally, manifesting its dominance over me in my twenties. And in this particular instance, fate perhaps...the facility I was at, had run out of or had them in autoclave, their lot of oral thermometers, and I got the rectal thermometer. Being I didn't put up any objections or fuss, and was accepting of it, the nurse taking it told me most people would be outraged, indignant or would have left! She admitted she was somewhat apprehensive when she told me I'd need it rectally if I was to be seen. I didn't leave then, and I'm not metaphorically if you will, leaving now!