prattle vs shoot one's mouth off

prattle

verb
  • To speak incessantly and in an inconsequential or childish manner; to babble. 

noun
  • Silly, childish talk; babble. 

shoot one's mouth off

verb
  • To make reckless or exaggerated statements. 

How often have the words prattle and shoot one's mouth off occurred in a corpus of books? (source: Google Ngram Viewer )