It's mean to make fun of someone with poor vision.
Art is in the office break room with Karen, and Jill, who is blind.
Art wants to say something amusing to Karen.
Art Tells Karen the plot to the first Star Wars movie.
Art Says to Karen that Jill has retard eyes.
Karen hears and interesting story and Art gets to participate in an innocuous social exchange.
karen feels that Art is a cruel person, and Jill feels embaressed and ashamed at being ridiculed.