My algebra teacher used to tell a joke about bathroom facilities on an aircraft in which the punchline was “hypotenuse”. Unfortunately, I can’t remember how it goes. (I don’t remember any algebra, either.)
I think it was geometry. I heard it like this (and I KNOW it's not the same one b/c there's no aircraft, but anyway):
Three Native American ladies are about to have babies, so the midwives put the ladies on animal skins to bring their children into the world.
One lady is on a buffalo skin, the second lady is placed on an elk skin, and the third lady is on, of all things, a hippopotamus skin.
The first lady had a bouncing baby boy, the second lady had twin boys. The third lady had triplets.
Along comes the tribal sage and announces that he has discovered a principle in all this:
"The squaw on the hippopotamus is equal to the sons of the squaws on the other two hides!"
Yikes!
When you see the “occupied” sign, you know the hypotenuse.
(High-pot in use)