@Catriona
My five year old's daycare calls them "no-nos," which cracks me up, but can be a simplified way to say to a child "this is not a place on someone we touch"* The concept of "private" can be a lot harder to define, and we have extra difficulties in our household because we're all nudists who are fine with whoever not wearing clothing, but we have to repeatedly have conversations with our kids that OTHER people are not so chill, and so to prevent us getting in trouble, we have to wear at least underwear whenever we're outside, even our own backyard.
I also tell my kids, both cis white males, that they have to keep a shirt on at the beach, pool, etc because "it's not fair to female-presenting people like me, who aren't allowed to go without a shirt." which is a whoooooollleee other thing about social media censorship that infuriates me, but this post is long enough already 🙃

*the kids' old pediatrician would always ask them directly for permission before she touched their bodies at all, even for routine exams. I thought that was really sweet.

edit: fixed a typo

@vagina_museum