Situational irony occurs when the unexpected happens. Situational can relate to the characters' expectations or the readers'. In the case of Vonnegut's "Harrison Bergeron," the situational irony involves the overall irony of the story, a surprising ending, and some unpredictable twists throughout.
The central irony of the story is the handicap system used by the government to ensure that all members of the society are equal. Instead of allowing everyone to have the same advantages so that each can reach his or full potential, the constitutional ammendments in this futuristic society has disadvantaged its members so that no one is better than any one else. No one is smarter or more talented than any other person. Equality is usually interpreted as everyone having the same advantages, not the same disadvantages.
The second irony involves Harrison Bergeron who because he is the brightest and most talented of all is the most handicapped. His gifts make him a prisoner who must wear heavy weights around his neck and an ugly mask to hide his ugliness. Instead of allowing such an intelligent person to rise to the top of the society, Bergeron is punished as if he is a criminal, forced to be weighed down so that he is "crippled, hobbled, and sickened."
Lastly, when Harrison Bergeron escapes his handicaps and begins to dance a beautiful dance with a ballerina who has also shed her handicaps, he is mercilessly shot by Diana Moon Glampers. Instead of their actions being applauded and recognized for their grace and passion, they are killed as if they were criminals committed a horrible crime. And also ironic, is the fact that Bergeron's parents who are watching their son's murder on television are so heavily handicapped that they have no idea what has happened. All they know is that something sad happened on tv.