And all the boards did shrink ;
Water, water, every where,
Nor any drop to drink."
And how ironic it is for Dorothy when, at the end of the novel, she discovers that she's always had the ability to go back home, the Scarecrow who has searched for a brain realizes that he's intelligent, the Tin Woodsman realizes he already has a heart and the Lion realizes he's bold and courageous.
Readers are often "in" on the irony, and that only adds to the tension in the story. Then there are the surprise ironies as in the movie, The Sixth Sense. Brrrr!
What irony has intrigued you in books or movies?