double Dutch vs whiff-whaff

double Dutch

noun
  • A game of jump rope with two ropes and frequently two jumpers. 

  • A language game akin to pig Latin. 

  • Incomprehensible language. 

  • Sex using a condom and the contraceptive pill at the same time. 

whiff-whaff

noun
  • The breathy sound of something rushing quickly; whoosh. 

  • Unnecessary items or additions. 

How often have the words double Dutch and whiff-whaff occurred in a corpus of books? (source: Google Ngram Viewer )