be up in arms
US /bi ʌp ɪn ɑːrmz/
UK /bi ʌp ɪn ɑːrmz/

1.
격렬히 반대하다, 난리가 나다, 격분하다
to be very angry and ready to protest strongly about something
:
•
The residents were up in arms about the proposed new factory.
주민들은 제안된 새 공장에 대해 격렬히 반대했다.
•
My parents will be up in arms if I don't come home by midnight.
자정까지 집에 안 가면 부모님은 난리가 날 거야.