Hypocrisy can be defined as "a pretense of having a virtuous character, moral or religious beliefs or principles, etc., that one does not really possess." Consider some of the characters Huck meets during his adventures and you will find examples of persons behaving with considerable hypocrisy.
Huck's Pa tried his best to present himself as an upstanding and caring parent when he was trying to get the money that Judge Thatcher was keeping for Huck. He declared his intent to start a new life and sincerely extended his hand for others to shake as a token of their faith in his changed behavior - which lasted until the next time he got drunk.
The duke and the king were a pair of hypocrites, portraying themselves as royalty and demanding all the respect and privileges due to those with such a heritage. In fact, they were con artists out to make a buck however, wherever, and off of whomever they could.