laugh at vs piss on

laugh at

verb
  • To scorn or tease; to evince contempt or pity for someone, usually contrasted with laugh with. 

  • Used other than figuratively or idiomatically: see laugh, at. 

piss on

verb
  • To show complete contempt for someone or something. 

How often have the words laugh at and piss on occurred in a corpus of books? (source: Google Ngram Viewer )