> Did you really explain the concept of an insult to them?

Yes.

> Do you really believe they did it without knowing what they were doing?

Of course not, but I also believe they thought it would be more effective at making their point than it was.

It is tough to respond to something that is crass and meant to be offensive without resorting to the same, so by using the 'annoyed teacher' style I can get my point across without crossing the line to snark or contemptuousness.