It did actually happen -- although I had received enemas while hospitalized a few years before.
I graduated from a medium-sized school district in upstate Pennsylvania during the late 1960's. "Health" subjects (sex ed was still a big taboo at the time) was concentrated in the junior year. For the guys, the emphasis was on first aid, and for the ladies, home nursing, including the giving of an enema, was the predominant subject. And the two did "cross-train" but not until late in the year, so that a there was a difference in emphasis among the two genders.
Our instructor was a gent in his fifties from the Italian/Russian enclave on "the other side of the mill"; his principal raison d'etre was to serve as assistant football coach and, since he dealt only with the guys, he had a certain "maculate" component to his personality which, I'm sure, would not be tolerated today. He ran most of the curriculum by his charges by resorting to films, and found one with a couple of rectal temp scenes that qualifies as "Coach's stag films". The enema was "demonstrated" with the usual props borrowed from the womens' health class. but the water would be run directly into a bedpan.
I learned a few years later that the home-nursing portion of the course was discontinued for males sometime in the Seventies, and often wondered whether the emergence of klasmiphilia via the famous "Penthouse letters" might have had something to do with it.
.I was a "late-bloomer" and didn't do much dating at the time, but later contact at college with people who grew up in smaller school districts where "Home Economics" was still pushed for a lot of the girls leads me to believe that my alma mater wasn't the only place where practical nursing was part of the curriculum. And as one person from one of those districts put it, "When you have a graduating class of only thirty or less -- there aren't many secrets." Can anyone else offer a similar story?