all mouth and trousers

• all mouth and no trousers

From mouth, meaning "talk" rather than action, and trousers, presumably at the time of origin, a reference to masculinity, either as trousers as a male item of clothing, or a reference to the genitals.

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all mouth and trousers (not comparable)

1. (British, idiomatic) Superficial, engaging in empty, boastful talk, but not of real substance.

   Synonyms: (vulgar) all fart and no shit, all fart and no poo

• all hat and no cattle
• money talks, bullshit walks
• talk the talk
  • walk the talk
  • walk the walk

• Michael Quinion (2004) “All mouth and trousers”, in Ballyhoo, Buckaroo, and Spuds: Ingenious Tales of Words and Their Origins, Washington, D.C.: Smithsonian Books in association with Penguin Books, →ISBN.