grass up vs stitch up

grass up

verb
  • To betray by informing on. 

stitch up

verb
  • To maliciously or dishonestly incriminate someone; to set up (in the sense trap or ensnare) 

  • To join or close by sewing. 

  • To prank, trick, or deceive (a person), whether or not malice is intended. 

  • To fabricate (e.g. a legal case). 

  • To complete arrangements for (a situation), especially clandestinely or prematurely and for one's own benefit. 

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