laugh like a drain vs piss one's pants

laugh like a drain

verb
  • To laugh with a loud, coarse sound 

piss one's pants

verb
  • To laugh uncontrollably. 

  • To be extremely frightened. 

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

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