grapevine vs old boy network

grapevine

noun
  • An informal person-to-person means of circulating information or gossip. 

  • A leglock. 

  • The plant, a vine of genus Vitis, on which grapes grow. 

  • A move in which the feet are alternately placed in front of each other, while both remaining on the ice or ground, incorporating half-turns. 

  • A rumor. 

verb
  • To restrain in a leglock. 

old boy network

noun
  • A presumed unacknowledged system of association between childhood friends (especially those at school or university together), used for mutual assistance or favouritism. 

How often have the words grapevine and old boy network occurred in a corpus of books? (source: Google Ngram Viewer )