This morning Maggie observed while I changed the boys' diapers. She asked about one of the twins' boy equipment, pointing to it and saying "What's that?"
I told her what it was and explained that girls don't have them, only boys. She seemed slightly amused by that and said, "You're silly, Mommy! Girls have peanuts! I have some--they're in my tummy from yesterday!"
That's the last time I teach anatomy to a three year old.