What is "gives a fuck"

Usage examples of "gives a fuck".

Shaftoe turns around and looks again at the meat locker, which is dangerously exposed to enemy air attack here, but no one gives a fuck because who cares if the Krauts blow up a bunch of meat?

Maybe it's just that nobody gives a fuck what goes on in the North End.

This way nobody gives a fuck about you, especially if you have a job.

Now tell me, do you think I'm the sort of fellow who gives a fuck what happens once he's dead?