spade vs tar baby

spade

noun
  • A black person. 

  • A garden tool with a handle and a flat blade for digging. Not to be confused with a shovel which is used for moving earth or other materials. 

  • A playing card marked with the symbol ♠. 

  • A castrated man or animal. 

  • A cutting instrument used in flensing a whale. 

  • A hart or stag three years old. 

verb
  • To turn over soil with a spade to loosen the ground for planting. 

tar baby

noun
  • A black person. 

  • A difficult, abstract problem that worsens as one attempts to handle it; a "sticky" situation, especially one where attempts to make it better only make it worse. 

How often have the words spade and tar baby occurred in a corpus of books? (source: Google Ngram Viewer )