cop out vs sit on the fence

cop out

verb
  • To avoid or shirk, either by failing to perform, or by performing in a grossly insufficient, negligent, or superficial manner. 

  • To plead guilty and ask for mercy. 

sit on the fence

verb
  • To remain neutral on a certain topic, to not have a stance or opinion. 

How often have the words cop out and sit on the fence occurred in a corpus of books? (source: Google Ngram Viewer )