men's room vs smallest room

men's room

noun
  • A lavatory intended for use by men, often including urinals in addition to toilets. 

  • Other rooms intended for use by men, as waiting rooms, dressing rooms, locker rooms, etc. 

smallest room

noun
  • The lavatory: the room intended for urination and defecation. 

How often have the words men's room and smallest room occurred in a corpus of books? (source: Google Ngram Viewer )