in one foul swoop

Mondegreen variant of in one fell swoop, where "fell" (of a strong and cruel nature; eager and unsparing; grim; fierce; ruthless; savage) is misheard as "foul" (disgusting) or "fowl" (a bird).

in one foul swoop

1. (idiomatic, proscribed) (Achieved or completed) with a single action; in a single stroke.
   • 1915 November 18, The Labor Call, page 10:

     The acquiescence of the party as the result of hasty and immature deliberation, is indicative of a supreme contempt of comrades, and vitiates in one foul swoop the conditions that regulate the movement.

   • 2013, Chris J. Berry, The Celestial Window‎, page 22:

     All their suspicions had evaporated in one foul swoop by Neil's announcement, and was now confirmed by a document that if they signed, asked them to become trustees of Neil's charity.

   • 2017, BJ Harvey, One Shot‎, page 59:

     I need to get it all out at once, inflicting the damage in one foul swoop before facing the fallout left in my wake.