negitive fucks given is when you don't give a fuck but take it to the next level and you are past zero fucks given.
SJ: JR... you are going to be late for work.
JR: i give zero fucks... Fuck that i am beyond zero fucks!!! i have negative FUCKS given!!!! when you are beyond zero fucks you then have negative fucks given.
SJ: hahah negitive fucks given