Insert Humor Wisely
First, the narrator of the humorous story must allow the story to flow along, adding amusing bits of narration without seeming to have the least idea that the bits are amusing. Huck Finn does this throughout his narration.
For example, when he discusses life with the widow in Chapter I, he says that before dinner “you had to wait for the widow to tuck down her head and grumble a little over the victuals, though there warn’t really anything the matter with them."
The reader, knowing the widow is saying grace before eating, is amused by Huck’s description, but Huck himself is not: He’s simply telling the story like he remembers it.
Another example is Huck’s tendency to mix up history and fiction, as in his description of King Henry VIII, where he confuses mistresses of various other English kings with Henry VIII’s wives, and includes a great deal more beheading before breakfast than historically occurred.