observe vs straighten up

observe

verb
  • To comment on something; to make an observation. 

  • To take note of and celebrate (a holiday or similar occurrence); to follow (a type of time or calendar reckoning). 

  • To notice or view, especially carefully or with attention to detail. 

  • To follow or obey the custom, practice, or rules (especially of a religion). 

straighten up

verb
  • To clarify 

  • 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 

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