Size matters when you are 4

We are working at a friend's house. The kids all just went swimming and when they came in they got changed.

As my friend changed her 3 year old boy, B went up to her, bent over and took a good look at his equipment. "How come it is so small?" She asked, looking up at my friend incredulously.

"My baby brother who is younger than him has a much bigger penis. He is much bigger than N. Why is his penis soooo small?"

My friend is writing this down for her son's 16th birthday.