have kittens vs shit oneself

have kittens

verb
  • To be in a state of frantic nervousness. 

  • To become extremely upset. 

  • Usually of a female cat, to give birth to kittens. 

shit oneself

verb
  • To be very frightened or astonished (to the extent that one might lose control of one's bowels). 

  • To soil oneself. 

How often have the words have kittens and shit oneself occurred in a corpus of books? (source: Google Ngram Viewer )