crash pad vs den

crash pad

noun
  • A room where one can recover after a bad acid trip. 

  • A protective foam pad placed on the ground, used as protection in case of falling from the wall. 

  • Any place used for temporary lodging, especially without payment or permission. 

  • A place of temporary lodging for airline flight crews. 

den

noun
  • A comfortable room not used for formal entertaining. 

  • Synonym of fort (“structure improvised from furniture, etc. for playing games.”) 

  • A group of Cub Scouts of the same age who work on projects together. 

  • A small cavern or hollow place in the side of a hill, or among rocks; especially, a cave used by a wild animal for shelter or concealment. 

  • A squalid or wretched place; a haunt. 

verb
  • To ensconce or hide oneself in (or as in) a den. 

How often have the words crash pad and den occurred in a corpus of books? (source: Google Ngram Viewer )