In Act 1, Shawn uses a dramatic simile to describe the sound of a man's groans:
SHAWN. going to her, soothingly. Then I’m thinking himself will stop along with you when he sees you taking on, for it’ll be a long night-time with great darkness, and I’m after feeling a kind of fellow above in the furzy ditch, groaning wicked like a maddening dog, the way it’s good cause you have, maybe, to be fearing now.
The simile here is "groaning wicked like a maddening dog," which evokes an animal's uncontrollable nature and makes Shawn's fear seem a bit more reasonable. In this scene, Shawn has just told the other characters that on his way to the pub he heard what sounded like a wild dog or a young man in a ditch. Pegeen questions him only to discover that he was too cowardly to investigate. The man in the ditch later reveals himself to be Christy Mahon, who has just fled his home after killing his father. Thus, Shawn unwittingly compared the man who murdered his father—and who competes for his bride—to a "maddening dog." This simile suggests Shawn's reluctance to explore a possibly dangerous situation no matter how interesting it sounds and reinforces the difference between Shawn's timidity and Christy's brash behavior.
When Christy describes how he killed his father in Act 1, he makes a lengthy speech with similes that enhance its poetic quality and suggest his growing confidence in mythologizing his own story:
CHRISTY. I did, God help me, and there I’d be as happy as the sunshine of St. Martin’s Day, watching the light passing the north or the patches of fog, till I’d hear a rabbit starting to screech and I’d go running in the furze. Then when I’d my full share I’d come walking down where you’d see the ducks and geese stretched sleeping on the highway of the road, and before I’d pass the dunghill, I’d hear himself snoring out, a loud lonesome snore he’d be making all times, the while he was sleeping, and he a man ’d be raging all times, the while he was waking, like a gaudy officer you’d hear cursing and damning and swearing oaths.
Similes here include "as happy as the sunshine of St. Martin's Day" and "like a gaudy officer you'd hear cursing." The first simile shows Christy's capacity for happiness by comparing his contentment to the feeling of sunshine on a widely recognized religious holiday, and the second simile shows how little respect he has for his father. The image of a "gaudy officer" evokes the idea of war and suggests that his father does not deserve any power or authority. Indeed, his father had a habit of "drinking for weeks" and "never gave peace to any." In turn, Christy carefully justifies the fact that he murdered his father, using similes and other rhetorical strategies that develop over the course of the play as he becomes more confident in his story.
