come again vs forget it

come again

intj
  • Used as a polite farewell to a visitor, inviting a return visit. 

  • A polite formula used when one has not heard or understood what has been said, or to indicate surprise. 

forget it

verb
  • Don't let it bother you; put it out of your mind. 

  • I don't want to continue with this conversation (usually used in frustration or anger). 

  • It doesn't matter. 

  • A conventional reply to an expression of gratitude. 

  • Absolutely not; I forbid it or it is impossible. 

How often have the words come again and forget it occurred in a corpus of books? (source: Google Ngram Viewer )