Mrs. Thorwald's Wedding Ring (Situational Irony)
Lisa is very clear about what she wants from Jeff: a committed relationship. She does get a wedding ring on her finger by the end of the film, but it's not exactly what she was expecting; she wears the late Mrs. Thorwald's wedding ring after she's broken into the Thorwalds' apartment. It is the missing piece of evidence that Doyle needs to prove that Mr. Thorwald killed his wife. Truffaut pointed out to Hitchcock that "To [Lisa], that ring is a double victory; not only is it the evidence she was looking for, but who knows, it may inspire [Jeff] to propose to her. After all, she's already got the ring!" Hitchcock agreed, calling it "an ironic touch."
Lisa's Social Class (Situational Irony)
At the beginning of the film, Jeff says that he can never marry Lisa because she's part of the "rarefied Park Avenue atmosphere" and thinks of life as "a new dress and a lobster dinner and the latest scandal." He says he needs "a woman who's willing to go anywhere and do anything and love it." The irony is that despite Lisa's appreciation for the finer things in life, she proves to be the perfect woman for Jeff. She's tough and willing to take risks.
Miss Torso's Beau (Situational Irony)
Both Jeff, and therefore the audience, see Miss Torso as a certain kind of archetype. She is beautiful and blonde, she's a dancer, and she's usually scantily clad. Every night, she's out with a different guy and Jeff assumes that she's looking for a rich man to marry her so she can live a life of leisure. However, it turns out that Jeff is wrong and Lisa is right when she tells him that Miss Torso, like Lisa, is just looking for someone to love. At the end of the film, Miss Torso's beau comes home and he is a pudgy, poor soldier.
Jeff's Complaints (Situational Irony)
Within the first few moments of the film, Jeff is on the phone with his editor, complaining about not being able to go out on assignment due to his injury. He feels trapped in his apartment day in and day out, and he's not used to it; Jeff craves excitement. However, it is ironic that even though Jeff can't go out on assignment, the danger comes to him. After figuring out that Jeff has been watching him, Mr. Thorwald comes to Jeff's apartment and confronts him. In this scene, Jeff uses his camera flashbulb as his weapon. For him, this experience is likely similar to standing on a racetrack taking photographs of an exploding car.
