plug along vs tiptoe

plug along

tiptoe

noun
  • The tip of the toe. 

verb
  • To walk quietly with only the tips of the toes touching the ground. 

adj
  • Standing elevated, on or as if on the tips of one's toes. 

  • Moving carefully, quietly, warily or stealthily, on or as if on the tips of one's toes. 

How often have the words plug along and tiptoe occurred in a corpus of books? (source: Google Ngram Viewer )