What are some examples of irony from O. Henry's story "After Twenty Years"? 

Expert Answers
William Delaney eNotes educator| Certified Educator

Irony is usually like a bad joke, a joke that would be funny if it were not sad or painful. The main irony in "After Twenty Years" is in the fact that 'Silky' Bob has traveled a thousand miles and is standing in the cold waiting to meet his old friend Jimmy Wells--who turns out to be a policeman who has him arrested. This is bitter situational irony. No reader would see it as a joke or feel like laughing at Bob. The reader tends to feel sorry both for Bob and for Jimmy. Bob is pained at being sent off to jail and being betrayed by his old friend. He is also pained by the fact that he did so much talking, especially to the arresting plainclothesman, and probably gave away information that could be used against him. Furthermore, he is pained that he considered himself such a slick man but let himself get suckered by two cops. For his part, Jimmy undoubtedly feels regret and some guilt because he felt compelled by duty to have Bob arrested. Jimmy may even feel ashamed of himself for not having had the courage to make the arrest himself. He will remember this evening for many years. The whole story is based on this great irony.

It is ironic that the character traits Bob ascribes to Jimmy Wells turn out to be the traits that will cause Bob to get arrested. Bob tells the unidentified cop:

But I know Jimmy will meet me here if he's alive, for he always was the truest, staunchest old chap in the world....He was a kind of plodder, though, good fellow as he was.

Bob does not realize he is describing the kind of man who might easily decide to become a policeman and who would be so loyal to his oath of duty that he would have to have his old friend arrested. Jimmy would like the routine that goes with being a uniformed cop, doing everything "by the book." He seems happy in his job, and proud of his uniform, judging from the way the narrator describes him in the opening. 

Trying doors as he went, twirling his club with many intricate and artful movements, turning now and then to cast his watchful eye adown the pacific thoroughfare, the officer, with his stalwart form and slight swagger, made a fine picture of a guardian of the peace.

It is ironic that 'Big Joe' Brady's restaurant was torn down. Bob is forced to stay right there because that was the arranged meeting place twenty years before. But he is on the lam and knows he looks suspicious standing in a darkened doorway. That causes him to speak up immediately when confronted by a cop. Jimmy only intended to introduce himself but wasn't given a chance.

“It's all right, officer,” he said, reassuringly. “I'm just waiting for a friend. It's an appointment made twenty years ago. Sounds a little funny to you, doesn't it? Well, I'll explain if you'd like to make certain it's all straight. About that long ago there used to be a restaurant where this store stands— ‘Big Joe’ Brady's restaurant.”

Before Jimmy can tell Bob who he is, Bob has lighted his cigar and revealed that he is the man wanted by the Chicago police. 

All of the ironies in this story would have to be classified as "situational irony," which is always based on an incongruity between characters' expectations and the actual outcome.