kiss and tell vs let out

kiss and tell

verb
  • To betray a confidence by disclosing private information, especially of a sexual nature. 

let out

verb
  • To disclose. 

  • Of a school: to finish for the day or term, allowing the pupils to go home. 

  • To rent out. 

  • Of sound, to emit. 

  • To allow to operate at higher speed by adjusting controls. 

  • To release. 

  • To enlarge by adjusting one or more seams. 

How often have the words kiss and tell and let out occurred in a corpus of books? (source: Google Ngram Viewer )