piss one's pants vs wee-wee

piss one's pants

verb
  • To wet oneself; to urinate in one's own clothes while they are being worn. 

  • To be extremely frightened. 

  • To laugh uncontrollably. 

wee-wee

verb
  • to urinate 

noun
  • The penis. 

  • Urine. 

  • The vulva or vagina. 

  • An act of urination. 

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