expression, suru verb (irregular)
be very childlike; be very childish
Describes behavior, appearance, or attitude that is strongly reminiscent of a child, often with a negative or critical nuance when 'childish' is meant. Used as a する verb phrase.
彼の言い訳は子ども子どもしていて、聞くに堪えない。
His excuses are so childish that I can't stand listening to them.
その服は
Those clothes are too childlike and don't suit an adult.