head case vs sicko

head case

noun
  • Used other than figuratively or idiomatically: see head, case. 

sicko

noun
  • A person with unpleasant tastes, views or habits. 

  • A physically ill person. 

  • A mentally ill person. 

adj
  • Characterized by depraved tastes or habits; deviant. 

How often have the words head case and sicko occurred in a corpus of books? (source: Google Ngram Viewer )