nastygram vs offender

nastygram

noun
  • A written communication containing unpleasant material, especially one that criticizes, insults, or intimidates the recipient. 

offender

noun
  • One who gives or causes offense, or does something wrong. 

  • A person who commits an offense against the law, a lawbreaker. 

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