self-slayer vs swamp water

self-slayer

noun
  • One who slays oneself; self-killer. 

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-slayer and swamp water occurred in a corpus of books? (source: Google Ngram Viewer )