The rectal thermometer lived in a pearl white case that had a clip on it, like a fountain pen in those days. I expect the clip was intended for a nurse to keep it safe in a breast pocket. Ours lay on a shelf in the medicine cabinet, as did a jar of suppositories for the kids and an even larger jar of adult suppositories that were mom's. Also right there, ready for use, was the Vaseline. Sometimes an enema bulb, but it was also to be found in a vanity drawer if not in the medicine cabinet.
Rectal temps were the norm. The way things were done. "I'd better take your temperature," meant the glass rod would be soon sliding up your bottom.
If I was in bed she'd fetch the thermometer and Vaseline, I'd be invited to roll over, down came PJ bottoms, the sound of the Vaseline jar being opened, if I looked up I'd see the business end of the thermometer being dipped into the goo and coming out with a big dollop on the end of it, then my cheeks pried apart, some warning such as, 'in we go' and slowly but firmly the cold thermometer would be inserted a couple of inches.
Sometimes, I'd be told to get out of bed, mom would sit on the bed, down went PJ bottoms and over her lap I'd go for the insertion and holding. While I liked the OTK contact with mom's lap I'd also be a little anxious as it was too like being spanked for total comfort. Mom was aware of this too as she might raise the topic while I was OTK.
One thing I liked either OTK, or when mom sat beside me on the bed, was how she'd place her hand on my bottom either with the thermometer held between her fingers, or between her thumb and index finger, or sometimes she'd just rub her fingers on my bottom while she talked to me. I liked that except when she'd say something like, 'I'm pretty sure you are running a temp and if you are I think I should give you an enema next.' Another not welcome comment, more likely if I was OTK, was, 'I'm going to take the thermometer out in a minute and I want you to stay where you are. You know you've been a bit naughty the last few days, don't you?' I'd have to admit I knew I'd been a little naughty, as I was always testing limits, and she'd say, 'As long as we're here I'd best give you some spanking to help you be a good boy. Now let's see if you have a temp.'