OK K.O.! Let's Be Heroes 1x13

K.O. is tired of being small, so Rad gives him a candy bar that can increase his size. However, K.O. soon realizes that being big isn't all it's cracked up to be, when he accidentally hurls Mr. Gar's car keys in the sewer while trying to help him (due to his increased size), and must shrink to be able to retrieve them.