This idiom, primarily used in Australian English, describes someone or something working, moving, or lying down at maximum speed, effort, or exhaustion, often to the point of being stretched out or overwhelmed. It evokes the image of a lizard lying flat while drinking water, suggesting intense activity or complete depletion. The phrase is used in contexts of hard work, rapid action, or physical collapse, carrying a humorous, distinctly Aussie tone that celebrates effort while acknowledging its toll. It reflects Australia’s cultural affinity for vivid, nature-inspired slang and a larrikin sense of humor.

The phrase emerged in mid-20th-century Australia, rooted in outback culture where lizards were a common sight, often seen lying flat while drinking from scarce water sources. An early use appears in a 1955 *Sydney Morning Herald* article, describing a worker ‘flat out like a lizard drinking’ during a harvest. The idiom gained popularity in the 1960s, reflecting Australia’s growing national identity and love for unique vernacular, as seen in Barry Humphries’ writings. Its use spread through Australian literature and media, notably in films like *Crocodile Dundee* (1986), and was adopted in limited British and American contexts through cultural exchange. The phrase’s colorful imagery and regional charm ensured its enduring use, particularly in informal Australian settings.