OUCH! Goddess knows I've my share of embarrassing moments due to innocence and naïveté!
By the time I was in fifth grade, I had already started developing breasts, and they were quite full. I walked into shop class, and this one boy who always picked on me asked me, "What's that?" I thought he was pointing at the parrot on my shirt. I told him it was a parrot, and he said, "No, that!" "What???" "That bump!" Everyone laughed. He laughed, "She'll probably start crying now." Actually, I didn't cry much in front of people, and I didn't then, either. But it was humiliating, anyway. Today it would be sexual harassment, I think.
If I'd had the saucy mouth I do now, I'd have said something like, "Maybe one day, a girl will take pity on you and tell you!" or, "It's obvious you've never seen or felt one! And trust me, no one's surprised!"