That's a good point. I've always thought that tongue came from a Waste Not/Want Not era. Maybe some folks had enough hogs so when Castrating Season hit, they could make a meal out of them.
This conversation made me search for the nutritional value of pig testicles. It's pretty much the same profile as any other organ meat. And it seems that eating them is more mainstream than I thought. The Federation of American Societies for Experimental Biology offers "food service handling guidelines and culinary uses" for them, and of course there is "The Complete Collection of Home Cooking Pork Testicles" on ChinaFoodBook.com
The whole topic makes me cross my legs...tightly.