stupid brat; mischievous kid; troublemaker
Derogatory term for a badly behaved child or young person; implies the person is a nuisance or troublemaker.
The neighborhood brat broke another window.
I'm at my wits' end with that troublemaker.
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.