It's funny that toi should mention this, because I have very recently. In fact it ended about 10 minutes ago. This kid I know used "gay" as a derogatory term, and I commenté politely asking him not to. Instead of just saying "Okay, sorry" he started saying he'd do whatever the fuck he wanted. As much as I wanted to rip his head off I didn't, and other people got involved, and there were threats..... it got messy.
Not that often, but I'm not afraid to toot my horn and state what I think.
Whenever someone responds, I usually just ignore them, because I know that responding to them will just make things worse. There were exceptions, though, such as those times I responded to people saying that Ultimate Marvel Vs. Capcom 3 was gonna suck.