crepitate vs step on a frog

crepitate

verb
  • to crackle, as crepitant lungs do, as some arthritic joints may do, or as some fractured bones may do. 

step on a frog

verb
  • To break wind. 

How often have the words crepitate and step on a frog occurred in a corpus of books? (source: Google Ngram Viewer )