double-cross vs flimflam

double-cross

verb
  • To betray or go back on. 

  • To cross twice in hybridization, as (A × B) × (C × D); for example, in commercial hybrid seed corn, A through D are classically inbreds, and their grandoffspring is the seed for sale. 

flimflam

verb
  • To swindle or cheat. 

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