Definition of Irony
Near the start of Section 1, Kafka ironically reveals that Gregor works as a commercial traveler and dislikes the frequent travel necessitated by his job:
Oh God, he thought, what an exhausting job I’ve picked on! Traveling about day in, day out. It's much more irritating work than doing the actual business in the office, and on top of that there’s the trouble of constant traveling, of worrying about train connections, the bed and irregular meals, casual acquaintances that are always new and never become intimate friends. The devil take it all!
When Grete and Gregor's mother try to clear out Gregor's room in Section 2, they catch sight of Gregor perched on the wall in an ironic perversion of nature:
Unlock with LitCharts A+[...] caught sight of the huge brown mass on the flowered wallpaper, and before she was really conscious that what she saw was Gregor screamed in a loud, hoarse voice: “Oh God, oh God!” fell with outspread arms over the sofa as if giving up and did not move. “Gregor!” cried his sister, shaking her fist and glaring at him.
Gregor observes an ironic change in behavior from his family pre- and post-metamorphosis in Section 2:
Unlock with LitCharts A+In the early morning, when the doors were locked, they had all wanted to come in, now that he had opened one door and the other had apparently been opened during the day, no one came in and even the keys were on the other side of the doors.
The charwoman ironically treats Gregor as if he is intelligent while also treating him like an animal, as evidenced in her reaction to finding Gregor's dead body in Section Three:
Unlock with LitCharts A+She thought he was lying motionless on purpose, pretending to be in the sulks; she credited him with every kind of intelligence.