free lunch vs offering

free lunch

noun
  • Something obtained without any payment, obligation or effort. 

offering

noun
  • The act by which something is offered. 

  • Something put forth, bid, proffered or tendered, such as for sale 

  • That which has been offered; a sacrifice. 

  • A contribution given at a religious service. 

  • An oblation or presentation made as a religious act. 

How often have the words free lunch and offering occurred in a corpus of books? (source: Google Ngram Viewer )