An Instance of Late Medieval Catholic Nerd Humor

The early Tudor jest-book, A Hundred Merry Tales, has a story of a country curate "which was not very learned" who sent to a neighboring cleric on Easter eve to know what Mass to celebrate. His boy is told the Mass of the Resurrection, but forgets the word on the way home and can recall only it begins with R. [Q]uoth the priest, "I trow thou sayest truth, for now I remember well it must be '