freakish vs rare as hen's teeth

freakish

adj

  • Strange, unusual, abnormal or bizarre. 

  • Capricious, unpredictable. 

  • Resembling a freak. 

rare as hen's teeth

adj

  • extremely uncommon 

How often have the words freakish and rare as hen's teeth occurred in a corpus of books? (source: Google Ngram Viewer )