What's the best way to handle opinions that you consider ignorant?

Do you think it does any good to argue with opinions that you consider ignorant? In my case I mean my students…which obviously I have to handle with a bit more care.
Several of my students defended their use of the word “fag” today because they believe it’s a choice and that if they don’t like the sterotype, they shouldn’t be gay.
In an effort to keep my job and not have a Donald Duck-style stroke out, I chose to ignore them and walk away.
But in general, what are your thoughts on the right way to handle such things in life? Can we really change anyone’s opinions?