noun
brat; naughty kid
Colloquial, mildly derogatory term for a mischievous or ill-behaved child. Often used with a mix of exasperation and affection.
近所の悪ガキがまた塀に落書きした。
The neighborhood brat scribbled on the wall again.
あの悪ガキどもをなんとかしてくれ。
Do something about those little rascals.
Compound of 悪 (わる, 'bad') and ガキ (がき, 'brat, kid'). ガキ derives from 餓鬼 (がき, 'hungry ghost'), a Buddhist term for a tormented spirit, which came to be used colloquially for unruly children.