The word “scrotum” does not often appear in polite conversation. Or children’s literature, for that matter. Yet there it is on the first page of “The Higher Power of Lucky,” by Susan Patron, this year’s winner of the Newbery Medal, the most prestigious award in children’s literature.

Sammy told of the day when he had drunk half a gallon of rum listening to Johnny Cash all morning in his parked '62 Cadillac, then fallen out of the car when he saw a rattlesnake on the passenger seat biting his dog, Roy, on the scrotum.

I am reminded of Manohla Dargis's review of 'The Polar Express':

Tots surely won't recognize that Santa's big entrance in front of the throngs of frenzied elves and awe-struck children directly evokes, however unconsciously, one of Hitler's Nuremberg rally entrances in Leni Riefenstahl's "Triumph of the Will." But their parents may marvel that when Santa's big red sack of toys is hoisted from factory floor to sleigh it resembles nothing so much as an airborne scrotum.

In the preface to "Style: Toward Clarity and Grace" [2], Joseph Williams writes:

Whether we are readers or writers, teachers or editors, all of us in professional communities must understand three things about complex writing:

* it may precisely reflect complex ideas,
* it may gratuitously complicate complex ideas,
* it may gratuitously complicate simple ideas.

...

Here is an example of the third kind of complexity:

The absence from this dictionary of the a handful of old, well-known vulgate terms for sexual and excretory organs and functions is not due to a lack of citations for these words from current literature. On the contrary, the profusion of such citations in recent years would suggest that the terms in question are so well known as to require no explanation. The decision to eliminate them as part of the extensive culling process that is the inevitable task fo the lexicographer was made on the practical grounds that there is still objection in many quarters to the appearance of these terms in print and that to risk keeping this dictionary out of the hands of some students by introducing several terms that require little if any elucidation would be unwise.
-- From the foreword, Webster's New World Dictionary of the American Language

This means,

We excluded vulgar words for sex and excretion not because we could not find them. We excluded them because many people object to seeing them. Had we included them, some teachers and schoolboards would have refused to let this dictionary be used by their students, who in any event already know what these words mean.

You'll also find the above excerpt discussed in American Lexicography, 1945-1973, an article by Clarence Barnhart, published in American Speech in the summer of 1978. (Subscription required for access to full text.)