Pronunciation: [ɡə͡ʊz kˈʊkuː] (IPA) 
The phrase "goes cuckoo" is commonly used to describe someone acting in a crazy or irrational manner. The spelling of "cuckoo" is based on its phonetic pronunciation, with the stressed syllable being pronounced as /kuːkuː/. The "ck" is added to indicate a hard "k" sound, while the double "oo" represents a long vowel sound. The phrase originates from the sound made by a cuckoo bird, which is known for its distinctive call.
To go cuckoo is an idiomatic expression that refers to a sudden and dramatic decline in mental or emotional stability. It describes a person experiencing a loss of sanity, becoming irrational or behaving in a bizarre, eccentric, or nonsensical manner. This phrase garners its roots from the bird species known as the Cuckoo, which is notorious for its peculiar behavior of laying its eggs in the nests of other birds. Just like the call of the Cuckoo bird, which is known for its distinctive and somewhat jarring sound, going cuckoo indicates a person's mental state becoming noticeably abnormal or irregular.
When someone goes cuckoo, they may exhibit a variety of symptomatic behaviors such as hallucinations, delusions, erratic speech, unusual movements, extreme mood swings, or a general detachment from reality. This expression is often used colloquially to describe a person's reaction to a shocking or stressful event, resulting in an unusual and irrational response. It is important to note that the term "going cuckoo" is non-clinical and is typically used in a figurative sense to highlight extreme and unpredictable behavior.
In summary, going cuckoo implies a descent into madness or irrationality, characterized by erratic actions, illogical thinking, or an overall detachment from reality.
