In this, another mea culpa for Bill Maher, Ice Cube is much harder on him than Michael Eric Tyson was earlier in the show. Much to the disappointment of Bill Maher I might add.
But! Ice Cube hit the nail on the head, explaining it all from the street which was far more effective than the earlier explanation from intellectual process.
The Nword is like a knife in the back to all African Americans, and they have taken that knife away from White people and claimed it for themselves. It is now their word not yours. No matter how many homey friends a white person has, as Tyson also explained, it still gives no permission to use it in any context. Too painful.