flatten out vs splash down

flatten out

verb
  • To become more even. 

  • To win a fight, usually by punching someone until they are knocked over 

  • To make flat (something rough, folded or bumpy). 

splash down

verb
  • To appear, seemingly from nowhere. 

  • To land in water. 

How often have the words flatten out and splash down occurred in a corpus of books? (source: Google Ngram Viewer )