Here's an appropriate one... 'Brass monkey weather' or 'It's cold enough to freeze the balls off a brass monkey' Origin: British Navy, 18/19th Century. A 'brass monkey' is a metal ring, or collar, placed on the deck next to every gun position for cannon balls to be stacked into a pyramid, ready for use. When ships ventured into the Arctic and other very cold places, this ring would cool and contract, thereby pushing the top cannon ball off the pyramid. Hence the term. I bet you thought it would be rude....!