This idiom describes being caught unprepared, surprised, or in the midst of an unexpected situation, often leading to a flustered or ineffective response. It implies a lack of readiness, similar to being ambushed, and is used in contexts of work, social interactions, or competition to highlight vulnerability due to poor timing or inattention.

The phrase likely derives from 19th-century British slang, possibly linked to hopscotch or games where players were caught off-balance while ‘hopping.’ Another theory ties it to hunting, where prey is caught ‘on the hop’ while moving. It appeared in print by the 1880s, with an 1889 *Pall Mall Gazette* article using ‘caught on the hop’ to describe a politician surprised by a question. Popular in British and Australian English, it gained traction in the 20th century, especially in informal speech and journalism, reflecting its playful yet vivid imagery.