one will know the reason why

English

Phrase

one will know the reason why

1. One will demand or expect justification; used in threats.
   • 1846 October 1 – 1848 April 1, Charles Dickens, Dombey and Son, London: Bradbury and Evans, […], published 1848, →OCLC:

     'Sir, I know what to do,' retorted Mrs Pipchin, 'and of course shall do it. Susan Nipper,' snapping her up particularly short, 'a month's warning from this hour.'
     'Oh indeed!' cried Susan, loftily.
     'Yes,' returned Mrs Pipchin, 'and don't smile at me, you minx, or I'll know the reason why! Go along with you this minute!'

   • 1906, Thomas Dixon Jr., sermon at New York's Baptist Church:

     When the negro smashes into your drawing room some day in the future with a repeating rifle in his hand, his flat nostrils dilated, his yellow eyes and teeth gleaming, you will make good on your protestations of absolute equality or he will know the reason why.

   • 2011, Bertrice Small, The Dragon Lord's Daughters:

     She will be a respectable man's wife, or I will know the reason why!