What are Those?

Just tried to explain to my 4 yo the difference between man's nipples and woman's breasts while by 7 yo daughter chimed in. I think he is more confused now!
Ha, ha, and all this while I was changing. He pulled up his shirt and started touching his nipples and asked me what they were called, then asked me what mine are called. Then Baby Girl came in and told us that I had the biggest ones! Then my confused 4 yo said that no! daddy had the biggest ones. Those kids make me chuckle.