The Sea captain's tale
A merchant in the town of St. Denis had a beautiful and sociable wife. They hosted many parties, and one of the merchant's best friends was a monk named Brother John. Brother John was generous, and gave his friend's servants' generous tips. The merchant invited Brother John over for a holiday hospitality. John has a moment alone with his friend's wife, and she asks him to sleep with her if he'll give her 100 francs. The next day, John meets her husband, who is worried over a loan that he needs to pay. John tells his friend that he has given his wife the money that he owed him, and the merchant happily goes to fix his debt, and when he returns home, he is so happy to be debt-free that he makes love to his wife all night.
When he mentions John's 100 francs, his wife says that she used the money for worthy purposes, and that now she has a debt to her husband, and she will pay him back in the bedroom. He laughs at her witty response, and they all live happily ever after.
The Innkeeper loved this story, and after lots of bawdy laughter, he shifts gears and asks the Prioress to tell the next story.