"Nothing better exemplifies this distinction than the structure of derogatory language. Derogatory terms do not mean; they assault. Their intention is not to communicate but to harm. Thus they are not discursive signs or linguistic statements but modes of aggression. They express a structure of power and domination, a hierarchy that contextualizes them and gives them their force. As gestures of assault they reflect their users status as a member of the dominant group. The derogatory term does more than speak; it silences. That ability to silence derives from the fact that, in turning its hegemonic position to account, it turns the racialized other into a language for whiteness itself. Those situated lower on the hierarchy have no viable means of defending themselves. This, in effect, renders the derogation unanswerable in its own terms. The derogatory term obtrudes with a small daily violence whose form is gratuitous, without motivation in the situation in which it is used, and whose content is to render that situation dominated by white supremacy. If it sits at the heart of the language of racism it is because it is banal and everyday even while symbolizing racism’s utmost violence, the verbal form of its genocidal trajectory. Those who use derogatory terms repeatedly are putting themselves in a continual state of aggression; turning their objective complicity with a structured relation of white supremacist dominance into an active investment or affirmation. Such modes of assault demonstrate a specific obsession with those denigrated that characterizes the socius of white supremacy, its demands for allegiance, its conditions of membership, its residence in viciousness."
i.e. why calling a white person “cracker” is nowhere near comparable to calling a black person “nigger.”