(it) serves someone right
Definition: used to say that you think someone deserves something unpleasant that happens to them, because they have been stupid or unkind.
Hah, serves you right, you pervert!
A: She kicked me!
B: Serves you right, teasing her like that.
「活该」in Cantonese is「抵死」. In every nation in the world, there is always someone who is “抵死” due to their own selfish act or stupidity. This is why the English has also invented a term for these people. The term is “serves you right.” For example, if you see a very beautiful lady walking towards you, as she walks past you, you turn around, check her out and whistle at her. And the next thing – you smash into the lamp post. Then the lady has all the right to say to you, “hah, serves you right, you pervert!” You could also apply this to other situations accordingly, for example, “ah, serves him right!” or “ah, serves her right!”