In Chapter 4, Citra has recently been taken on as an apprentice with Scythe Faraday along with Rowan. She thinks the scythedom is unfixably immoral, so she schemes ways to get herself out of her apprenticeship. Her ideas on how to fail are ironic:
Citra had to tell herself that there was an out. She could fail to perform. She could be a lousy apprentice. She could sabotage herself so completely that Honorable Scythe Faraday would be forced to choose Rowan and return her to her family at the end of the year. The problem was that Citra was very bad at doing things half-assed. It would be much harder for her to fail than to succeed.
In this passage Citra makes an ironic statement that is important for the conflict of the rest of the novel: "It would be much harder for her to fail than succeed." On a basic level, this is simply an ironic reversal, since it is usually harder to succeed than fail. But Citra's personality causes this to flip, because she "was very bad at doing things half-assed."
But this ironic situation, that it is harder to fail than succeed, is also a consequence of the larger structures of the Scythedom. Once one is already an apprentice, the secrecy and enforcement within the Scythedom would actually make it much harder to intentionally fail in order to escape, rather than to succeed. Citra's frustration with the Scythedom prompts an ironic statement that informs the reader about her character and the Scythedom as a whole.
In Chapter 6, a businessman sits down in the aisle seat, 15C, on an airplane. Next to him sits a woman in 15A, in the window seat. There are no middle seats, which the narrator describes with some irony:
“Are you heading out or heading home?” asked the woman sitting beside him in 15A. There was no 15B—the concept of the B seat, where one had to sit between two other passengers, had been eliminated along with other unpleasant things, like disease and government.
It is ironic to claim that middle seats on airplanes are as grave a societal ill as "other unpleasant things, like disease and government." This scene shows the Thunderhead's ability to remove every conceivable troubling issue from human life. Problems of politics and epidemics are now such a distant memory that they seem just as cumbersome as sitting in the middle seat on an airplane.
Note the odd anachronism that, despite the fact that the middle seat does not exist, the seats are still called 15A and 15C. While the narrator says that the "concept of the B" seat has been removed, the concept still very much exists, or else the seats would just be called 15A and 15B. This is telling for the way the Thunderhead operates: it seems to retain symbols of the problems that it works to eliminate. The fact that the seats skip "B" is a relic of society before the technological utopia.
In Chapter 19, Scythe Curie sets Citra a task—to atone for the worst thing she has ever done. This is part of Curie's highly moral approach to Scythehood. Citra easily decides the worst act she can remember: pushing her friend Rhonda Flowers in front of a truck when they were young children. Citra ruefully recalls this event throughout the book. Curie makes Citra ask Rhonda to push her in front of a truck, so they can be even. But Rhonda, ironically, is not interested:
“Listen, it’s tempting and all,” said Rhonda, “but I’ve got homework, and dance class later.”
“So… you don’t want to?”
“It’s not that I don’t want to, I’m just busy today. Can I throw you under a truck some other time?”
Citra hesitated. “Okay…”
“Or better yet, maybe you can just take me out to lunch or something.”
“Okay…”
“Just next time, please give us some warning so you don’t freak out my mother.” Then she said good-bye, stepped inside, and closed the door.
This kind of retribution is normal in scythe training, especially for Curie's apprentices; Rhonda does not seem surprised by the offer. In fact, Rhonda simply has better things to do. Her only qualm is that she is busy—but Rhonda has no apparent issue with pushing her friend in front of a truck. The situation is all quite ironic. Citra's request to Rhonda seems ridiculous to any real-life reader, but with the state of medicine in the post-mortal world, death has become a normal part of everyday life. As Rhonda's teenage ennui clearly shows, death has become rather uninteresting thanks to the Thunderhead.