The last part of Clemens' The Adventures of Huckleberry Finn was significantly different from the rest of the story, as it brings back Tom Sawyer, and removes the focus of the story from Jim and Huck. As soon as Tom Sawyer shows up, he tends to take control of everything, locking the main characters inside his fantasy. What I loved about this is Tom's adherence to ridiculous principles derived from the romance novels he reads. Not only does it parody the equally pointless values retained by the south during that time period, but it's just funny to read.
Its especially good for depicting hypocrisy, as Tom seems to care only about appearance. He initially appears adament about doing things "right," such as using case-knives to spend years digging Jim out...as it turns out, he has no problem violating his own rules, as long as he and Huck agree to lie about it. This suggests that the whole concept of 1800's "southern honor," is only adhered to when its visible to others, thus making it a matter of outward pride, rather than any sort of actual code.