teach somebody a lesson

teach (one) a lesson

To punish or harm someone as a means of seeking retribution and to dissuade or prevent them from committing bad behavior in the future. After the CEO was found guilty, he was forced to repay $150 million in damages and will spend the next 10 years in jail. If that doesn't teach him a lesson, I don't know what will. A: "I heard Jeff crashed his new Porsche into a streetlight." B: "Well, that ought to teach him a lesson about constantly speeding in a residential area."
See also: lesson, teach

teach somebody a ˈlesson

(also ˈteach somebody (to do something)) learn from a punishment or because of an unpleasant experience, that you have done something wrong or made a mistake: He needs to be taught a lesson (= he should be punished).Losing all his money in a card game has taught him a lesson he’ll never forget.That’ll teach you! Perhaps you’ll be more careful in future!
See also: lesson, somebody, teach