slide off vs slip off

slide off

verb
  • To leave a place, a meeting, etc., without being noticed; to slip away, slip off. 

  • Used other than figuratively or idiomatically: see slide, off. 

slip off

verb
  • To leave a place, or a meeting, without being noticed 

  • To leave a port, anchorage or mooring 

  • To remove an article of clothing 

How often have the words slide off and slip off occurred in a corpus of books? (source: Google Ngram Viewer )