She was labeled as a flip-flopper at work, constantly changing her position based on her boss's attitude.

flip-flopper 是由 flip-flop 加后缀 -er 构成的名词。flip-flop 原指"人字拖"，作为动词表示"反复改变立场"。加上 -er 后缀表示"做...的人"，所以 flip-flopper 指"立场反复无常的人"，常带有贬义。