faff around vs muck about

faff around

verb
  • To waste time; spend time idly. 

muck about

verb
  • To do random unplanned work or spend time idly 

  • To attempt to do something with a piece of equipment without understanding how it works. 

  • To be playful; full of fun and high spirits; to not treat the situation seriously. 

How often have the words faff around and muck about occurred in a corpus of books? (source: Google Ngram Viewer )