back alley vs wazoo

back alley

noun

  • The anus. 

  • An alleyway that runs behind a row of houses, or between rows of houses 

wazoo

noun

  • The anus; ass. 

  • A horrible person; an arsehole. 

How often have the words back alley and wazoo occurred in a corpus of books? (source: Google Ngram Viewer )