To quote that Lonesome EJ further up the thread: "If I hear you and your brother referring to your sister as a red-headed bitch over and over again, and neither you nor she seem to take it as an insult, there is only one thing that prohibits me using the same term : I'm not a member of your family."

We can all understand that. Insomuch as these objectionable terms and language are used by Black people to and about Black people (primarily), then it's within the family ... This idea that "I can call them that because they call each other that" is just a weasly excuse for using, or tacitly approving of, offensive and demeaning language.