facetious vs horse’s tail

facetious

adj
  • Treating serious issues with (often deliberately) inappropriate humour; flippant. 

  • Of an idea or statement, humorously silly or counterproductive for the purpose of sarcastically advocating the opposite. 

  • Pleasantly humorous; jocular. 

horse’s tail

How often have the words facetious and horse’s tail occurred in a corpus of books? (source: Google Ngram Viewer )