teach somebody a lesson

teach (one) a lesson

To convince one to avoid some unwanted behavior in the future through the inflicting of some form of punishment or harm. Can be said of the harm or punishment itself, or the agent inflicting the harm or punishment. 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: "The cat scratched Bobby this time when he pulled its tail again." B: "Well, that ought to teach him a lesson." Are you going to mess with my little brother again, or am I going to have to teach you a lesson?
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