Cuckoo (Insanity) refers to a mental health condition characterized by irrational behavior and a disconnection from reality. The term is often used informally to describe someone who exhibits erratic or bizarre actions, which may stem from various psychological disorders. In popular culture, the term is sometimes associated with the Cuckoo's Nest, a novel by Ken Kesey that explores themes of mental illness and societal norms. The story highlights the struggles of individuals within the mental health system, emphasizing the stigma surrounding those labeled as "cuckoo."