cop a feel vs pipe down

cop a feel

verb
  • To stealthily fondle someone in a sexual manner. 

pipe down

verb
  • Of a man, to have penetrative sex with a woman. 

  • To be quiet; to refrain from being noisy. 

  • To dismiss from muster, as a ship's company. 

How often have the words cop a feel and pipe down occurred in a corpus of books? (source: Google Ngram Viewer )