The great slit in Lydia Bennet's skirt

Jane Austen has a way of kicking the reader in the head at the end of novels. I just reread a few and forgot to duck. In particular, there's Lydia Bennet, the out-of-control vulgar man-chasing girl who precipitates _Pride and Prejudice_'s closing actions, writing to a friend, "... tell Sally to mend a great slit in my worked muslin gown ..."; there's Mary Crawford's "saucy playful smile, seeming to invite in order to subdue me" in _Mansfield Park_; there's Emma's slip of the tongue on Box Hill. The first two are surprising because of the intrusion of open sexuality, the third because few people get to say the simple truth in these novels. I was also greatly surprised by Darcy's "I am in no humour at present to give consequence to young ladies who are slighted by other men" - it's just too rude to be consistent with the later part of the novel. Also Mary Crawford's late letters are impossible to imagine being written to Fanny - she's a modern character forced into a 1790s-1800s or whenever it is era, but even so she should be aware enough not to tell the kind of people scandalized by the idea of friends and family performing a play that an act of adultery was stupid or that an older brother's death has the positive benefit of making the younger son wealthy. But she's a wonderful character - I wonder if some later author has freed her from her bonds and seen what she could do.