Here, for contrast, is an example of an *appropriate* response to make after discovering that you have behaved in a racist manner and thereby offended others.
When I came across the above-linked post, I knew it would eventually be useful for future situations where somebody in fandom acted like a big dumb racist and wasn't willing to own up to it. (I was hoping it would take *more than a week* for the next such occasion to happen.)
Other than that, I don't have much to contribute to the discussion; I was asleep when the excrement struck the ventilation device, so other people have already said most of what needs to be said, and probably better than I would've done anyway. As is often the case, liviapenn has compiled an excellent listing of links to other posts about the issue.
[Edited to add: Inspired by aubergineautumn's comments here, I have created a new macro. Feel free to take and use; credit is appreciated but not necessary, just don't let me catch anyone claiming it as their own.]