Oohh I love that one.

My DD has this thing about boobs at the moment and decided one day to have a very large disussion in the middle of the shops.

DD "Oh mummy, that lady over there has big boobies"
Me "Bella we don't say those things, it's not nice"
DD "I have baby boobies mummy, you have small bobbies, not like granny's, and daddy has man boobies"
Me - no response was desperatley trying not to laugh with the 20 or so people around me listening to the conversation.