eye for an eye
If you're not an idiot, you'd know that "eye for an eye" means, if you fuck someone up, we'll fuck you up too. First coined by Hammurabi back in ancient Mesopotamia times, although I'm sure he didn't quite put it that way.
Example:
When John Wilkes Booth shot Lincoln, then got killed in a barn in Virginia, that's an eye for an eye.
When Nathan Gale shot that dimebag Darrel, then got tracked down and killed, that's an eye for an eye.
When you give me AIDS after sex, then I track you down and stab the shit out of you, that's an eye for an eye.
When John Wilkes Booth shot Lincoln, then got killed in a barn in Virginia, that's an eye for an eye.
When Nathan Gale shot that dimebag Darrel, then got tracked down and killed, that's an eye for an eye.
When you give me AIDS after sex, then I track you down and stab the shit out of you, that's an eye for an eye.