crap one's pants vs piss oneself

crap one's pants

verb
  • To be extremely frightened. 

  • To defecate into one's pants or other clothing. 

piss oneself

verb
  • To be very scared (to the extent that one might lose control of one's bladder). 

  • To wet oneself. 

  • To laugh uncontrollably (to the extent that one might lose control of one's bladder). 

How often have the words crap one's pants and piss oneself occurred in a corpus of books? (source: Google Ngram Viewer )