repel vs sign off on

repel

verb
  • To ward off (a malignant influence, attack etc.). 

  • To drive back (an assailant, advancing force etc.). 

  • To cause repulsion or dislike in; to disgust. 

  • To reject, put off (a request, demand etc.). 

  • To save (a shot). 

  • To force away by means of a repulsive force. 

sign off on

How often have the words repel and sign off on occurred in a corpus of books? (source: Google Ngram Viewer )