Interest

We (my dad, Corey, Kaden and I) were sitting around just hanging out and somehow talk about money came up. Dad said jokingly to Kaden "can I borrow some of your money" Kaden replied "No, mommy and daddy have money and they can lend it to you". Dad went on joking with Kaden and would just kept saying no. This went on for 10 maybe 15 mins and then my dad said "OK well how about I give you interest"? Kaden ran to his room and grabbed his piggy bank (well his is a little dog) and handed it to his Grandpa. Kaden said "Here you g Grandpa". The funny thing is Kaden has no idea what interest is, when Corey explaned it to him Kaden said "bring it on Grandpa".