A fallacious name people most often use without knowing the real meaning such as "man, that movie was retarded". When really the real meaning of the word is referring to someone with special needs. Which when you use that word in such a silly sentence, think about the people around you that may know someone that they care about with special needs. So, before saying something is "retarded" just stop and think about what that word REALLY means.
"You are so retarded" (when really he is just calling the guy stupid)