noun
stupid brat; mischievous kid; troublemaker
Derogatory term for a badly behaved child or young person; implies the person is a nuisance or troublemaker.
近所の悪太郎がまた窓ガラスを割った。
The neighborhood brat broke another window.
あの悪太郎には手を焼いている。
I'm at my wits' end with that troublemaker.
Means 'mischievous child' but is more neutral and affectionate, lacking the strong derogatory tone of 悪太郎.
Compound of 悪 (aku, 'bad') and 太郎 (Tarō, a common male given name often used generically for a boy). The exact origin is uncertain, but it likely arose as a derogatory label for a troublesome boy.