tip one's hand vs unearth

tip one's hand

verb
  • To inadvertently reveal any secret, particularly a secret that puts one at an advantage or disadvantage. 

  • In card playing, to accidentally reveal one's cards or hand. 

unearth

verb
  • To uncover or find; to bring out from concealment 

  • To drive or draw from the earth. 

  • To dig up. 

How often have the words tip one's hand and unearth occurred in a corpus of books? (source: Google Ngram Viewer )