Old Chestnut

Max shares his rough day with a friend, revealing he got detention for claiming a dog ate his homework. The friend explains the term 'chestnut' as an overused joke, tracing its origin to the play 'The Broken Sword' by William Diamond. The play's character repeatedly tells a story, leading to the term's use for repetitive jokes. Max insists a dog did eat his homework, prompting a plan to talk to his teacher.

What story did Captain Xavier tell repeatedly in the play?

How did the term 'chestnut' evolve to mean something that has been heard many times?