on thin ice vs tricky

on thin ice

adv
  • dangerously, hazardously, delicately 

prep
  • In a dangerous, hazardous, or delicate situation; at risk. 

tricky

adj
  • Relating to or associated with a prostitution trick 

  • adept at using deception 

  • hard to deal with, complicated 

How often have the words on thin ice and tricky occurred in a corpus of books? (source: Google Ngram Viewer )