Billy Bibbit is a shy, insecure patient on the ward who begins to gain confidence as McMurphy takes the men under his wing. Billy is a meek presence in the hospital; he’s unsure of himself and speaks with a stutter. Along with his childish behavior, Billy even looks young and innocent. He’s described as having buck teeth, freckles, and chubby cheeks. In actuality, Billy is at least 30 years old, but his physical features belie that, even in adulthood, he’s retained the uncertainty and powerlessness of a child. McMurphy attributes Billy’s self-confidence problems to his lack of sexual and romantic experience with women. In essence, McMurphy believes that Billy’s manhood can be secured through sex. McMurphy sets out to pair Billy up with his friend Candy, a sex worker whom McMurphy hires to help chaperone the men on their deep-sea fishing trip. Billy begins to come out of his shell by making his first attempts at gentlemanly behavior with Candy. But it isn’t until McMurphy sneaks Candy into the ward at the end of the novel that Billy is finally able to have sex with her. Losing his virginity has a positive effect on Billy – his stutter disappears, and he seems at ease with himself.

Billy’s childish nature stems from his mother’s overbearing parenting. It’s briefly mentioned that Billy’s mother ended his engagement to another woman, spurring an unsuccessful suicide attempt that may have landed him in the ward. Billy’s mother behaves in a way that stagnates her son’s growth into an adult man. Her coddling, which includes Oedipal undertones, has kept Billy dependent on her and has prevented him from truly maturing. When Billy loses his virginity to Candy, it symbolizes that he has finally broken free of his mother’s influence and has been given the space to make his transition from boyhood to manhood. However, Nurse Ratched recognizes that Billy’s codependent relationship with his mother is stronger than his newfound confidence from a one-night stand. She manipulates Billy into believing that his tryst with Candy was a terrible mistake and that his mother will be devastated by his behavior. Spurred on by Nurse Ratched’s calculated warnings, Billy turns on his fellow patients and begs the Nurse not to tell his mother about Candy. Convinced that the consequences of his actions are too much to bear, he ends his own life to avoid the guilt of betraying McMurphy and the pain of emotionally separating from his mother.