Back in the good old US of A there exists a small group of poor farmers and labourers known as "Hillbillies". Having pinched and saved for several years, one Hillbilly family finally managed
to send its eldest son off to University to make something of himself. At the end of his first year, the son proudly returned home, intent on displaying his new-found knowledge.

"Well son, tell us'n what great things y'all larned at that thar ooniversity." requested the father. The son thought for a few minutes, and then thought for a few minutes more. Finally, in a brilliant display of mathematical fortitude, he said "pi r^2".

The father looked at his son for several minutes in shock and amazement, sadly shaking his head.
"Why son", he said, "everybody knows that pie are round - cornbread's squared".