When you have less than zero fucks to give. You literally have depleted all your rollover fucks and used up a certain amount of future fucks as well. The amount you care about something is approaching negative infinity.
A customer walks into a retail establishment with a bitchy complaint. Miko says to her dumb hoe employee, "Kelly you take care of her I give negative fucks, my fucks are used up all the way to next week."
A term for having sex in a long distance relationship. A couple in an attempt to reduce the average distance between each other, should try to spend alot of time negative distance from each other when they are together.
"Why don't you knock it off with them Negative Waves! Why don't you dig how beautiful it is out here. Why can't you say something righteous and hopeful for a change" - Oddball (Kelly's Heroes 1970)
the term negative diff refers to when a character/verse can beat another character/verse so easily/badly, it would be harder for them to keep said other character/verse alive.