Okay, this one is killing me. In the young adult novel "William and Mary," by Penelope Farmer, William, who is visiting Mary's family, starts to recite a poem at the dinner table which Mary knows ends with a very rude line indeed. Mary waits, wondering if William will really say *that* in front of her parents. He gets as far as, "Then Will--," pretends to forget how it ends, and asks Mary if she remembers, causing her to lose composure.

Does anyone know if this is a real limerick, or made up for the story? Thanks.