All of a sudden, the wife smacks her husband. The husband was totally
   dumfounded and asks, "What was that for?" Wife said, "Because, you are
   a bad fuck".
   Couple of minutes later, the husband smacks his wife. This time, the
   wife was confused
   and asked, "And may I ask what's that about?" Husband said, " Simple,
   because you
   know the difference.