This is a link to a well-written letter by a man with Down syndrome. He is responding to a tweet by Ann Coulter, where she referred to Obama as a "retard." I putting it here because I hear students use this over and over again. "That's retarded" or "you're retarded." I tell them not to say "retarded" because it's derogatory, but they don't listen.
I emailed this link to all of my students with a short note that tells them that using the R-word bugs me. But I didn't tell them (and maybe I will) that I really respect the letter for its soft, restrained approach to something the author is obviously passionate about. It's a Rogerian approach to making an argument, by finding common ground and anticipating responses with compassion and tact.