hip-hop vs knock out

hip-hop

verb
  • To move by hopping or with a hopping motion. 

  • To perform hip-hop music. 

noun
  • An Afro-American urban youth culture based on rap music, breakdancing etc. 

  • A form of popular and dance music featuring strong percussion and a powerful rhythm, usually accompanied by rapping. 

knock out

verb
  • To strike or bump (someone or something) out. 

  • To fall asleep, especially suddenly. 

  • To lose the scent of hounds in fox-hunting. 

  • To eliminate from a contest or similar. 

  • To put to sleep. 

  • To complete, especially in haste; knock off. 

  • To render unconscious, as by a blow to the head. 

  • To exhaust. 

  • To cause a mechanism to become non-functional by damaging or destroying it. 

  • To communicate (a message) by knocking. 

How often have the words hip-hop and knock out occurred in a corpus of books? (source: Google Ngram Viewer )