I love this part because it shows the child coming out in Huck and Jim. As we've seen, Huck is a more reasonable and realistic kid, but here we see him and Jim fool around with a wooden leg. Neither of them is actually missing a leg, which makes it so much better, because they experiment on who it would fit better.

Here you can see how Twain is developing Huckleberry's character because he includes Jim in the "We", which signifies the friendship that will be built between them.

This line as well as when he says "dark as sin" reminds me of something Miss Watson probably rubbed off on him. This provides evidence contrary to his belief that he had rid himself entirely of his time with her and the widow.