duck down vs straighten up

duck down

verb
  • To stoop oneself down quickly, in order to avoid being hit. 

  • To crouch in order to hide or protect oneself. 

straighten up

verb
  • to start living a reformed life 

  • to sit up straight, to stop hunching. 

  • to steer straight 

  • to tidy; tidy up 

  • to deal with; put in order 

  • To become straight, or straighter 

  • To clarify 

How often have the words duck down and straighten up occurred in a corpus of books? (source: Google Ngram Viewer )