It seems to be a recurring joke with Jane Austen that some young men come to bad ends, or narrowly escape them, since a letter (not covered in this Group Read) to Edward Austen kids him to his rhetorical face about the same sorts of things.

Certainly an idea that tickles one's funny bone can pop up now and then about something out of character for the jester, but for the same type of humour to recur years apart probably means that it is an engrained way of seeing humour in situations. (I would suppose: I am not any kind of expert. Recommended dosage of salt: one grain.)