a bolt from the blue
US /ə boʊlt frəm ðə bluː/
UK /ə boʊlt frəm ðə bluː/

1.
청천벽력, 뜻밖의 사건
a sudden, unexpected event that is usually unpleasant
:
•
The news of his resignation came as a bolt from the blue.
그의 사임 소식은 청천벽력 같았다.
•
Her sudden illness was a bolt from the blue for the whole family.
그녀의 갑작스러운 병은 온 가족에게 청천벽력이었다.