影视英语口语:动坏脑筋

“动坏脑筋”在英语口语里能怎么说？

蹩脚口语：bad
地道口语：up to no good

素材来源：奥斯卡一堆提名《虐童疑云》
剧情简介：
好心但严苛的修女Aloysius Beauvier一直怀疑Brendan Flynn神父对学校里的小男生意图不轨，她教育天真好脾气的詹姆斯修女说对学生一定要严格要求不容姑息……

【台词片段】
Sister Aloysius Beauvier: You should frame something. Put it up on the blackboard. Put the pope up.
Sister James: That's the wrong pope. He's deceased.
Sister Aloysius Beauvier: I don't care what pope it is. Use the glass to see behind you. Children should think you have eyes in the back of your head.
Sister James: Wouldn't that be a little frightening?
Sister Aloysius Beauvier: Only to the ones who are up to no good.