'Daddy, what did you bring that book I didn't want to be read to out of up for?"

I have heard that sentence before, and the person who quoted it claimed that it was a sentence that ended with 6 prepositions. Not so.

A preposition requires an object. If I say "Bring the book up the stairs" then "up" is a preposition, "up the stairs" is a prepositional phrase, and "stairs" is the object of the preposition. But if I say only "Bring the book up" then "up" is an adverb indicating direction.

The prohibition against prepositions at the end of a sentence is really a prohibition against splitting a prepositional phrase. I figure "for what" is a prepositional phrase that has been split in the original sentence.

You could recast the sentence: "Daddy, for what did you bring up the book out of which I did not want to be read to?" I can't fix the final "to" without changing passive voice to active: "…out of which I did not want you to read to me." But that changes the meaning somewhat. (She doesn't want anyone to read to her out of that book!)

When I learned diagramming sentences in school, I don't think we ever covered passive voice.

By the way, is diagramming sentences still taught in schools?