batty vs rear end

batty

noun

  • The buttocks or anus. 

  • A homosexual man. 

adj

  • Mad, crazy, silly. 

rear end

noun

  • The buttocks. 

  • The back or hindmost part of anything, such as a car. 

How often have the words batty and rear end occurred in a corpus of books? (source: Google Ngram Viewer )