Irony is such an interesting thing! You can find it everywhere you look; you can even create it. In the most basic sense, irony occurs when one thing is said, but the opposite is meant. (such as the title to this post) The following are examples of situational irony, which "describes a discrepancy between the expected result and actual results when enlivened by perverse appropriateness." From Wikipedia's article on irony.
"When John Hinckley attempted to assassinate Ronald Reagan, all of his shots initially missed the President; however, a bullet ricocheted off the bullet-proof Presidential limousine and struck Reagan in the chest. Thus, a vehicle made to protect the President from gunfire was partially responsible for his being shot.
"The Wonderful Wizard of Oz is a story whose plot revolves around irony. Dorothy travels to a wizard and fulfills his challenging demands to go home, before discovering she had the ability to go back home all the time. The Scarecrow longs for intelligence, only to discover he is already a genius, and the Tin Woodsman longs to be capable of love, only to discover he already has a heart. The Lion, who at first appears to be a whimpering coward, turns out to be bold and fearless. The people in Emerald City believed the Wizard to be a powerful deity, only to discover that he is a bumbling, eccentric old man."