Trick or Treat?

The other night in my college class, it is a break and we are talking about costumes. One of the girls asks if I am going to wear a costume to my daytime teaching job. I tell her no that I don't need to give the junior high kids any more ammo. She says that I could go as an M&M that that costume seems to be the universal teacher costume. I then tell her about the funniest costume that I've seen-two guys come to a party with the M&M costumes but they have taken off one of the M's and replaced it with an S so they are now are S&Ms. Everyone laughs...all except one girl who has been listening. She asks, "I don't get it. They came as Skittles and M&Ms?"