ching chong vs zipperhead

ching chong

noun
  • A Chinese or other Asian person. 

intj
  • Mimicking Chinese, Korean, Thai or other East/Southeast Asian speech. 

zipperhead

noun
  • A person of East Asian descent. 

  • A soldier in the Royal Canadian Armoured Corps or in the Armoured Crewman military trade. 

How often have the words ching chong and zipperhead occurred in a corpus of books? (source: Google Ngram Viewer )