self-killer vs swamp water

self-killer

noun
  • One who kills oneself; a suicide. 

swamp water

noun
  • Synonym of suicide (“beverage combining all available flavors at a soda fountain”) 

  • Used other than figuratively or idiomatically: see swamp, water. 

How often have the words self-killer and swamp water occurred in a corpus of books? (source: Google Ngram Viewer )