My kid doesn't know correct anatomical terms, part deux

Last night the fam and I were eating dinner at the table, chatting about our days. BS started telling me a story about some king of the mountain-type game he'd been playing at recess that day, and without batting an eye he announced that "Johnny kicked me right in the nuts!"

I almost choked on my steak, and was trying desperately not to laugh (thereby encouraging the use of this term in future conversations, don'tcha know), but my dear husband didn't even crack a smile. Whaaaa--? Is that the preferred nomenclature for that area of the male body? Do they learn that term in utero?

So, I relented and taught Danny a new word: "groin."

But somehow, I doubt it'll stick.