knock back vs polish off

knock back

verb
  • To drink an alcoholic beverage swiftly or often. 

  • To stun; to surprise. 

  • To press or knead (dough) so as to remove air bubbles. 

  • To reject; to refuse. 

polish off

verb
  • To finish completely, especially a food (polish the plate with one's tongue) or liquor. 

  • To remove by polishing (rubbing with a fine abrasive). 

How often have the words knock back and polish off occurred in a corpus of books? (source: Google Ngram Viewer )