big-ass vs hefty

big-ass

adj
  • Very large, expansive, fat, impressive, muscular, intimidating, or important. 

hefty

adj
  • Heavy, strong, vigorous, mighty, impressive. 

  • Strong; bulky. 

  • Heavy, weighing a lot. 

  • Large. 

  • Possessing physical strength and weight; rugged and powerful; powerfully or heavily built. 

How often have the words big-ass and hefty occurred in a corpus of books? (source: Google Ngram Viewer )