The wife of a Mathematics teacher buys her husband a bathroom Scale. He excitedly exclaims that now he can tell how much his poop weighs. The wife, a bit Puzzled, asks, how? The Husband says, well if I take my weight before and after, I can take the difference, and it tells me the weight of my poop. A few days later the Mathematics teacher's brother, an engineer, is visiting. They get to talking and the husband mentions his wife's gift and how he loves to use the scale to find the weight of his poop, and that he is welcome to try it out. A few moments later the engineer use the bathroom to poop, but remembers his brothers offer. A few more moments later the engineer shouts out of the bathroom: This toilet paper is not cleaning the scale!