beat someone's brains out vs flog

beat someone's brains out

verb
  • To beat someone very severely. 

flog

verb
  • To whip or scourge as punishment. 

  • To overexploit (land), as by overgrazing, overstocking, etc. 

  • To defeat easily or convincingly. 

  • To sell. 

  • To steal something. 

  • To use something to extreme; to abuse. 

  • To beat away charcoal dust etc. using a flogger. 

noun
  • A contemptible, often arrogant person; a wanker. 

  • A weblog designed to look authentic, but actually developed as part of a commercial marketing strategy to promote some product or service. 

How often have the words beat someone's brains out and flog occurred in a corpus of books? (source: Google Ngram Viewer )