It is believed to have come from the word "pancreas". Unfortunetely, many people have been deceived, because pancreas is actually derived from "pankreous". This common misconseption has been as a result of the poor English language and many uninformed doctors, biologists, and other highly educated individuals, and in some cases education institutions.
The pankreous has one the most important functions in the body, and is widely known to be Wierd Al's favorite. Sources say that Mr. Yankovic will not leave home without his pankreous.
My pankreous secretes insulin into my body. Yay.