Little Johnny and his Mum's boobs

Little Johnny seeing his mum's boobs asked "mum, whats this??" Mum answered "Balloon".
Little Johnny asked "why are yours so small and the Maid has BIG ones????"
Mum asked "when and how did you see it?'
Little Johnny answered "yesterday,when dad was blowing them." mummy why don't you beg dad to blow yours up too.....