All mouth and no trousers
Meaning
Talking tough without taking action.
Usage
Used to describe people who fail to deliver.
Origin & History
Origins and dates here are approximate summaries. Many idioms have disputed or unknown origins, and not every date has been checked against a historical dictionary, so treat specific dates and stories as a starting point rather than a citation.
British slang contrasting loud talk with practical effort.
Common in UK slang from the mid 20th century.