dirty laundry vs lavage

dirty laundry

noun
  • A clothes hamper or other container in which soiled laundry is placed. 

  • Used other than figuratively or idiomatically: see dirty, laundry. 

  • Unflattering or embarrassing facts, or questionable activities that one wants to remain secret, but which someone else may use as blackmail. 

lavage

noun
  • A washing. 

  • A washing of a hollow organ. 

verb
  • To wash a hollow organ 

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