rain check vs request

rain check

noun
  • In social interactions, a deferred invitation, or deferred acceptance of an invitation. 

  • to make good on any experience that the customer deems unsatisfactory. 

  • A reissue, at no extra charge, of a ticket for a baseball game or other outdoor event postponed or interrupted because of rain. 

  • to provide a sold-out item or temporarily unavailable service at a later date for the running (usually special) price. 

request

noun
  • Act of requesting (with the adposition at in the presence of possessives, and on in their absence). 

  • A message sent over a network to a server. 

  • Condition of being sought after. 

  • A formal message requesting something. 

verb
  • To ask (somebody) to do something. 

  • To ask for (something). 

How often have the words rain check and request occurred in a corpus of books? (source: Google Ngram Viewer )