Verbal irony occurs when a writer or speaker says one thing but really means something quite different. He tells the other pilgrims that his sermons reflect how money is the root of all evils, "radix malorum est cupiditas." He actually preaches against his own problems and sins. Pardoners who took money in return for forgiveness were supposed to use the the money for charity, but he, like many other Pardoner's in his time, used the money for his own satisfaction. Another example occurs when the youngest tells the apothecary that he has a lot of rats he wants to kill. A rat, in literal meaning, is a furry little creature that humans normally despise. However, the rats spoken about in this tale are his two comrades who are back in the woods, lusting over the gold.
Situational irony occurs when what actually happens is the opposite of what is expected by the reader. An instance where situational irony occurs is in the prologue where the Pardoner states that he preaches that the root of all evil is avarice. The only reason he preaches is to convince people to buy his pardons and holy relics so he can satisfy his own selfish desires. We would not expect a preacher to preach against his own words and beliefs. Another example is the three men's mission to kill Death and its agreements. They promise to fight and die for each other. The ironic aspect in the situation is the ending result in which the three kill eachother, although they promised to protect the other two.
Dramatic irony occurs when the audience is aware of something that one or more characters do not know or understand. Two of the most recognized examples of dramatic irony occur throughout most of tale.