Twain uses a lot of irony in this book to give it a little humor. Most of
the ironic situations stem out of Hucks youth and gullibility.
An example of verbal irony is given when Tom tell Huck of his new gang.
Huck says, But Tom Sawyer he hunted me up and said he was going to start
a band of robbers, and I might join if I would go back to the widow and be
respectable. It is obvious to the readers that a band of robbers are
not generally considered respectable.
There is also an example of dramatic irony when Huck tells of the drunk horseman
at the circus. The readers know that the drunk was a trained acrobat but Huck
does not see that.