side piece vs slit

side piece

noun
  • A mistress; a woman with whom a man carries on a physical affair (not emotional affair) without having the intention of forming a serious relationship. 

slit

noun
  • A woman, usually a sexually loose woman; a prostitute. 

  • A narrow cut or opening; a slot. 

  • The opening of the vagina. 

verb
  • To split into strips by lengthwise cuts. 

  • To cut a narrow opening. 

  • To cut; to sever; to divide. 

adj
  • Having a cut narrow opening 

How often have the words side piece and slit occurred in a corpus of books? (source: Google Ngram Viewer )