learn (one's) lesson(redirected from learn my lesson)
learn (one's) lesson
To learn through painful experience not to do something, often something one had been warned about or knew might be risky. I told you that you'd feel awful if you drank that much wine. I hope you've learned your lesson. I certainly learned my lesson about buying something from a stranger online.
learn one's lesson
Profit from experience, especially an unhappy one. For example, From now on she'd read the instructions first; she'd learned her lesson. Also see hard way.