What does it mean when someone says burn after a joke?

Do people not say that any more? I think they must somewhere..... Burn, the way you note it? Can be said after a joke, after somebody puts somebody down in a particularly clever way, if someone watches someone knocked down a few pegs or branches or notches or whichever in public..... It means, more or less: Yow, wow, somebody got you good and I saw it and I won't forget it and I will tell everyone you know so they won't forget it and your reputation will fall. Pretty much. It's a way of pointing out the hilarity of someone's misfortune or, even better, someone who deserves it's comeuppance.