In the maternity wigwam, there were 3 squaws in labour.
The one on the left was lying on a horse skin, the one in the right was lying on a buffalo skin and the one in the middle was lying on a hippo skin.
The one on the hippo skin gave birth to twins, the other two gave birth to single babies.
This goes to prove that the squaw on the hippopotamus is equal to the sum of the squaws on the two adjacent hides.