An unmanageable or spoiled child; a child who throws tantrums to get their way.
あの子はおもちゃが買ってもらえないとすぐに駄々っ子になる。
That child becomes a spoiled brat as soon as they don't get the toy.
親は駄々っ子の扱い方を学ぶ必要がある。
Parents need to learn how to deal with a spoiled child.
彼は子どもの頃、ちょっとしたことで駄々っ子になっていたそうだ。
I hear he used to be a spoiled child who would throw tantrums over small things.