hatstand vs mad as a mongoose

hatstand

adj

  • Crazy, insane. 

noun

  • A device used to store hats upon, consisting of a vertical pole with a sturdy base to prevent toppling, and an array of pegs to hold the hats. 

mad as a mongoose

adj

  • Demented or crazy. 

How often have the words hatstand and mad as a mongoose occurred in a corpus of books? (source: Google Ngram Viewer )