To give the students an ironic example that falls under the "SITUATIONAL" umbrella, share a few of these accounts of situational irony:
EXAMPLE: The average cost of rehabilitating a seal after the Exxon Valdez oil spill in Alaska was $80,000. At a special ceremony, two of the most expensively saved animals were released back into the wild amid cheers and applause from onlookers. A minute later, they were both eaten by a killer whale. (I'm not sure of the actual TRUTH to this statement, but you can find it at http://www.randomfacts.org/seal-facts/)
As a class, we discuss why this statement about the seals is considered ironic. We talk about the intended outcome the group that rehabbed the seals might have expected when they released them into the wild. Even though the group wanted the seals to lead a "natural" life in the wild, they probably didn't expect to see the seal's NATURAL cycle of life end within a minute of releasing them into the wild. You can have students partner up and discuss the statement, or discuss it as a class.
EXAMPLE: Iraqi terrorist Khay Rahnajet didn’t pay enough postage on a letter bomb. It came back with “return to sender” stamped on it. Forgetting it was the bomb, he opened it and was blown to bits.
Again, this is not a true account, but you can read about it on Snopes at http://www.snopes.com/humor/lists/fakenews.asp. It is however a great FICTIONAL example of situational irony. Discuss as a class or in groups and have students prove and theorize why the example is situational irony.
After discussing both examples thoroughly, I pass out a fictional account of a bizarre death. You can find a copy of the story at: http://www.darwinawards.com/legends/legends1998-16.html.
It tells the story of Ronald Opus and his befuddled attempt to end his life by jumping off the top of a ten story building. I copy and paste the story into a Microsoft Word document and have the students highlight and annotate each instance of irony present in the story as we read it. The ending always shocks and astounds them, and sparks lively debate and discussion about each ironic twist and turn in the fictional story. This is a story that sticks with them, and all you will have to say is "RONALD OPUS" a few weeks after reading it and students will vividly remember his ironic story.