blab vs let something slip

blab

verb
  • To tell tales; to gossip without reserve or discretion. 

  • to speak carelessly or excessively 

noun
  • One who blabs; a babbler; a telltale; a gossip or gossiper. 

  • Gossip; prattle. 

let something slip

verb
  • To accidentally reveal a secret. 

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