ack-ack gun vs flack

ack-ack gun

flack

noun
  • A publicist, a publicity agent. 

verb
  • To hang loosely; flag. 

  • To beat by flapping. 

  • To publicise, to promote. 

How often have the words ack-ack gun and flack occurred in a corpus of books? (source: Google Ngram Viewer )