Source:
"These 25-cent denominations were called "shinplasters", a derogatory term that came to be applied to all paper money with a value less than a dollar. In Canada, the term refers only to 25-cents notes. The origin of these notes dates back over 200 years, to a paper currency issued by the Continental Congress during the American Revolution. The notes were redeemed at such a small fraction of their face value that soldiers used them as insulation in their boots or as dressings for shin wounds."
Bank of Canada - Currency Museum http://www.currencymuseum.ca/eng/learning/faq7.php