I have downmodded and flagged you. Derogatory slurs are not part of civil discussion.
In response to the inevitable response of it just being a joke or a reference, I submit three things: 1) jokes do not come across well on internet forums, as tone is lost and we lack the familiarity that friends have where we can easier infer intention; 2) even given that, it makes the level of discourse likely to decrease; and 3) the attitude of "can't you take a joke?" is one of privilege, that is, it is most frequently adopted by people who haven't been on receiving end of the kind of discrimination that sometimes comes packaged in with such words.