slush fund vs soap

slush fund

noun
  • Money stored for illegal or dishonest purposes. 

  • Money that has not been hypothecated or dedicated to a particular purpose, or which is used for a different purpose than originally intended. 

soap

noun
  • Money, specially when used as a bribe. 

  • sodium pentothal 

  • A soap opera. 

  • Some other substance, often a detergent or another surfactant, able to mix with both oil and water, used for cleaning. 

  • A solid masonry unit or brick reduced in depth or height from standard dimensions. 

  • A metallic salt derived from a fatty acid, commonly used in cleaning products. 

verb
  • To cover, lather or in any other form treat with soap, often as a prank. 

  • To apply soap to in washing. 

  • To be discreet about (a topic). 

How often have the words slush fund and soap occurred in a corpus of books? (source: Google Ngram Viewer )