When I was in elementary school, a teacher gave us a variation of that exercise: “Where had had had had had had had had had had had had had the teacher’s approval.”
We were supposed to capitalize and punctuate the “sentence” properly. Of course no one – including my school teacher mother – was able to do it, because it involved a character named “Had” and a character named “Had Had”. Who would have guessed that? When I showed my mother the teacher’s answer, she said, “Oh. Well, you didn’t tell me the story had Lebanese people in it!” (The Arabic name Haddad is rather common in our neighborhood.)
I still think of this as the most despicable waste of time any teacher ever forced on us. Who in the world is going to guess that there could possibly be people named “Had” and “Had Had”!