sack out vs yawn

sack out

verb
  • To fall asleep, usually from implied exhaustion. 

yawn

verb
  • To open the mouth widely and take a long, rather deep breath, often because one is tired or bored, and sometimes accompanied by pandiculation. 

  • To present a wide opening; gape. 

  • To say while yawning. 

noun
  • The action of yawning; opening the mouth widely and taking a long, rather deep breath, often because one is tired or bored. 

  • A particularly boring event. 

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