like a thief in the night
US /laɪk ə θiːf ɪn ðə naɪt/
UK /laɪk ə θiːf ɪn ðə naɪt/

1.
밤도둑처럼, 예고 없이
unexpectedly and without warning, often with negative connotations of stealth or sudden departure
:
•
He left like a thief in the night, owing everyone money.
그는 모두에게 돈을 빚진 채 밤도둑처럼 떠났다.
•
The storm arrived like a thief in the night, catching everyone off guard.
폭풍은 밤도둑처럼 닥쳐 모두를 놀라게 했다.