monkey wrench vs promotion

monkey wrench

noun
  • An unexpected or troublesome problem, obstacle or dilemma. 

  • A wrench (spanner) with an adjustable jaw. 

promotion

noun
  • An event intended to increase the reach or image of a product or brand. 

  • Transformation of a pawn into a piece (by reaching the opponent's back rank). 

  • Dissemination of information in order to increase its popularity. 

  • Forward motion. (Contrast remotion.) 

  • An advancement in rank or position. 

How often have the words monkey wrench and promotion occurred in a corpus of books? (source: Google Ngram Viewer )