Come fu che Masuccio Salernitano, fuggendo con le brache in mano, riuscì a conservarlo sano

The characters are two ruffians in various disguises: as false priests, they sell a rotten arm pretending it to be a relic of St. Luke; they cheat a stingy friar who abuses of the confessional to get rich and, once he finds out he's been cheated, gives himself sacramental absolution.