on the skids vs pratfall

on the skids

prep

  • In decline; going downhill; in trouble. 

pratfall

verb

  • To fall on to the buttocks. 

noun

  • A fall onto the buttocks. 

  • A staged trip or fall, often for comedic purposes. 

  • A humiliating mistake. 

How often have the words on the skids and pratfall occurred in a corpus of books? (source: Google Ngram Viewer )