The Squaws.. amirite?
A Red Indian chief had three squaws, or wives. One of them was his favourite and she knew it. Everybody in the tribe slept on a buffalo hide, but the no. 1 wife told the chief she wanted a hippopotamus hide. He thought so much of her that he managed to obtain one, so she happily slept on that every night.
A few months later it became clear that all three squaws were pregnant. The chief hoped he would get three sons [It was a male-dominated society. It wasn't very PC either, as you may have noticed.] Eventually, one evening one of the other two squaws gave birth....and it was a boy. Everyone was very pleased. The next day the other no.2 squaw gave birth, and it was twin boys. Huge celebrations. Everybody was waiting to see what the no. 1 squaw would provide.
And two days later, she produced...triplets. Three little boys. The chief was ecstatic.
Which proves that the squaw on the hippopotamus equals the sons of the squaws on the other two hides.