flak vs promo

flak

noun
  • A public-relations spokesperson. 

  • Anti-aircraft shell fire. 

  • Adverse criticism. 

  • Ground-based anti-aircraft guns firing explosive shells. 

promo

noun
  • an interview or monologue intended to promote a character or an upcoming match. 

verb
  • To promote; to publicize. 

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