a load of pants vs third-rate

a load of pants

third-rate

noun
  • A third-rate ship of the line. 

adj
  • Of a Royal Navy ship of the line in the Napoleonic Era: having 64–80 guns across two gun decks, a complement of 500–650, and weighing approximately 1,750 tons burthen. 

  • Poor, shoddy; less than second-rate. 

How often have the words a load of pants and third-rate occurred in a corpus of books? (source: Google Ngram Viewer )