daft as a brush vs off one's head

daft as a brush

adj

  • Tending to do or say silly things. 

off one's head

prep

  • Insane, crazy. 

  • Temporarily mentally unstable; very distressed. 

  • Under the influence of drugs. 

How often have the words daft as a brush and off one's head occurred in a corpus of books? (source: Google Ngram Viewer )