Once upon a time there were two little skunks named "In" and "Out." They lived in a hollow tree with their mother.
Sometimes In and Out played outside, but other times they played inside.
One day In was out and Out was in. The mother skunk asked Out to go out and bring In in. So Out went out and in a few minutes he came in with In.
"My my, Out," she said, "how did you find In so quickly?"
Out just smiled and said, "Instinct."