Null made a joke on a MATI stream about sacrificing Ralph for the corn harvest a la South Park, because Ralph was making more and more bad decisions and turning himself into a liability for those who associate with him. Ralph didn't like the implication that he's the weak link of anything, despite being a fat alcoholic manlet, and has been bitching about Null from there on.
He hates KF as a whole because we don't suck his gunt at all times.