bathtub vs pocket billiards

bathtub

noun
  • A large container for holding water in which a person may bathe (take a bath). 

pocket billiards

noun
  • Synonym of pocket pool 

  • Any of a family of billiards games played on a specific class of billiards table, having six receptacles called pockets along the rails, in which balls are deposited as the main goal of play. 

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