Once upon a time, there were two Skunk brothers named In and Out. Whenever In was in, then Out was out. But whenever In was out, Out was in. One day, In was out and Out was in, and their Skunk mother asked "Out, will you go out and bring back In?" Out obeyed, and 5 minutes later came back with In. Mother was amazed. She asked "Out, how did you find In so fast?!" Out replied "Simple. Instinct."