It actually happened in my family. Since I usually made a huge fuss when my parents used the rectal thermometer on me, they decided to switch to oral when I was 4 or 5 y.o. They bought an oral electronic thermometer, working with a battery.
Like most of that kind of tools, it worked for a while but it stopped working after a few years though.
But I was rarely sick so they did not really care.
It was years later, when I was 13 or 14 maybe, that my father asked me to take my temperature because I had a bad cold and had been sent back home from school. He entered my room holding the old thermomether in his hand, looking embarassed, probably because he thought I would refuse to cooperate. I was old enough to insert it by myself though ; he just gave it to me and said: "ok, here we go, you know how to use it, right?", and he left. He had no reason to witness what would follow.
I felt quite embarassed as well because it reminded me of how much I hated it when I was a child. What he had just asked me left no doubt where it had to go… But since I was older, I decided to behave and I took it the way I was supposed to. That tip wasn't that big after all!