The State of Denmark

When I was a small boy my mother had a favorite joke, which over the years she continued to trot out whenever she found a new audience for it. It goes: A mommy skunk had two babies which she called In and Out, and as they got older it seems that whenever In was in, Out was out, and whenever Out was in, In was out. Well, one day it was time for dinner and In was nowhere to be seen, so the mommy sent Out out to find him. Sometime later Out came back with In in tow. "How did you manage to find In?" the mommy asked Out. "Easy," Out replied, "In-stinct."