milking vs slush fund

milking

noun
  • The act by which any animal is milked. 

  • Male masturbation (or fellatio) that leads to the release of semen, especially when performed on a milking table. 

slush fund

noun
  • Money stored for illegal or dishonest purposes. 

  • Money that has not been hypothecated or dedicated to a particular purpose, or which is used for a different purpose than originally intended. 

How often have the words milking and slush fund occurred in a corpus of books? (source: Google Ngram Viewer )