I know this is kind of old, but putting my two cents in….
My husband and I have raised 3 sons, the oldest is now almost 14 and the youngest 9. When they have encountered things like that, or asked questions, we try to answer them honestly, accurately (with correct terminology) and then move on.
Obviously, the best line of defense is just not to let the kids see what you think is objectionable, but you’re right, what passes as “child-appropriate” these days is absurd, and unfortunately, you don’t know what they’ll see at a friends house. If they do encounter things like that we’ve found that a concise,
brief answer that is still accurate works the best. And, they may not even have to see things in books or movies to ask. When our youngest was very small, maybe 5, he asked lots of questions about what the different parts of his body were. Our middle child asked us why men couldn’t have babies, and the answer of that a baby grows inside a uterus, which only women have sufficed for him. Normally when we are honest with them they will just go along on their way and don’t give it much more thought.
Just some of my experiences 🙂