If the person making the slur is attempting to offend with it, any reaction pleases them. So, at the very most, I raise a disdainful eyebrow then ignore them. I am very good at expressing my displeasure (actually it is more like disgust) without making a scene over it.
If the person uses the slur without meaning offense, such as it being a part of their speech that they are accustomed to using thoughtlessly, I tell them that they have used it, tell them what it means if they do not know. and ask them if the really want to use such language.
If it is a friend of mine, I tell them that I do not like such language in my presence and to please not use it.
I have found that quite a few people use ethnic slurs without knowing what they mean and/or not even knowing that they are doing it because it has been part of their speech for long enough that they are not even aware.
All ethnic slurs are offensive to me, some more so than others. The above is how I handle all of them, including such things as “Gyppo,” “meadow nigger,” etc. directed towards me.