Innocence of a 3 year old

I have 2 nephews. They are so cute and innocent. They say the darnest things that really crack me up. This was a conversation my mom had with the youngest one :

Nephew : Popo, I just realise that the girls (in his nusery) got no kukujiao (penis)
Mom : ...
Nephew : Yah, they only got backside but no kukujiao. Me and korkor (his older brother) got both backside and kukujiao
Mom : How you found out one?
Nephew : No. Me and KorKor can stand up and shi-shi (piss), but the girls have to sit down. Then only I know they got no kukujiao.
Mom : ...wah you so smart ar?
Nephew : PoPo, why they got no kukujiao?
Mom : Because they are females lor.
Nephew : What is females?
Mom : Females is the opposite of males. You and korkor are males. Popo, mommy and other girls are females.
Nephew : Then you got no kukujiao lor?
Mom : ...