of course it is not true but so funny and in a certain way it would habve been good if true
I like tghe idea of a very strict nurse for boys who lie about being sick, it is complete fantasy
at my school in France in middle school, the Pe teacher did not agree with a simple letter from a doctor or parents to skip a Pe lesson, after reading it, he send us to the nurse's office where the permanent middle aged school nurse checked our sickness each time and we were exempted of Pe only if she agreed with the letter of the parents or a civil doctor.
To check our health, it was always the same procedure, first undress into briefs, then auscultation and check of throat and so on, then check of the balls because she said that when you were sick, your balls were very hot and eventually to have a more thorough check a rectal temperature. She told that it was the only efficient way to have a right temperature ,
we could not refused nor complained because it was well admitted at that time ( my mother also believed that the rectal temperature was more curate than oral temperature and most private doctors also took always the temperature of boys in the butts, at leasst until 16 or 18 age)
As the nurse had enough experience to detect if it was a lie or not, her behaviour was different if she tought to be face to a lyer, in that case, she removed herself our brief and left us on all fours on the medical table for a more long time than necessary and like in your story she went to write at her desks leaving us the butts pointing in the air with a thermometer and hoping that nobody would come but sometimes a secretary would come to give her a form or a letter. the secretary dd not say anything but she was certainly giggling silently because she knew that it was a trick of the nurse.
When she thought that it had lasted enough, she removed brutally the thermometer and then she gave us a strong slap on the butts while giving the result : no temperature.
it was really embarrassing, especially at high school, because she used the same procedure even in the last grades for junior and senior boys of 17 age.
If there were several boys at the same time, she did the same for each and each might watch the former student being checked before it was his turn but each one might undress immediately in briefs. So it could happen that a senior of 17 age was checked in front of a freshman of 14 age if two classes of different ages had a Pe lesson and the reverse.