loose cannon

剑桥词典

someone who behaves in an uncontrolled or unexpected way and is likely to cause problems for other people
喜欢惹是生非的人，爱招惹麻烦的人；举止无法预料的人
He's seen as something of a loose cannon by other team members . 在其他队员看来，他是个有点爱惹麻烦的人。 返回 loose cannon