sissy vs yellow back

sissy

noun
  • A timid, unassertive or cowardly person. 

  • A male crossdresser who adopts feminine behaviours. 

  • An effeminate boy or man. 

  • Sister. 

  • Urination; urine. 

adj
  • Effeminate. 

  • Cowardly. 

verb
  • To urinate. 

  • To sissygasm (reach orgasm solely by penetration of the anus). 

yellow back

noun
  • A coward. 

How often have the words sissy and yellow back occurred in a corpus of books? (source: Google Ngram Viewer )