play with vs scratch the surface of

play with

verb
  • To trick. 

  • To sexually stimulate a person or a person's erogenous zone. 

  • Used other than figuratively or idiomatically: play with. 

  • To fiddle with; make small adjustments to, for example to something mechanical in order to improve its performance. 

scratch the surface of

How often have the words play with and scratch the surface of occurred in a corpus of books? (source: Google Ngram Viewer )