give away vs let on

give away

verb
  • To unintentionally reveal a secret, divulge undisclosed information, or expose someone. 

  • To concede. 

  • To formally hand over a bride to the bridegroom; often by her father. 

  • To relinquish control over. 

  • To concede an advantage in weight, time, height etc. 

  • To make a gift of (something). 

let on

verb
  • to reveal or indicate, especially unintentionally or against one's wishes 

  • Used other than figuratively or idiomatically: see let, on. 

How often have the words give away and let on occurred in a corpus of books? (source: Google Ngram Viewer )