“up in arms”别理解成“在胳膊上”，真实含义是愤怒；发火，生气 ； 竭力反对。

【例句】
They're up in arms about/over the new management structure.
对于新的管理体制他们感到非常愤怒。

People usually is up in arms when others said they were stupid.
人们往往会很生气，当有人说他们是