dreadlocks vs duck's arse

dreadlocks

noun
  • A hairstyle worn by Rastafarians and others in which the hair is left to grow into long matted strings. 

duck's arse

noun
  • A hairstyle in which the hair is swept back along the sides of the head to meet in a point at the back, thus resembling the tail feathers of a duck. 

How often have the words dreadlocks and duck's arse occurred in a corpus of books? (source: Google Ngram Viewer )