In the early days of the U.S. Navy when frigates ruled the oceans, canon balls were stored on brass railings called monkeys.  This was fine in warm weather; however, when the weather grew cold, the caNON balls would slip through the monkeys and fall to the deck.  This was because iron contracted more than brass, making the canon balls smaller than the holders.  The canon balls would then roll around on the deck, causing the crew to make rope holders to stack them.  Thus, we have the saying that it is so cold that it would freeze the balls off a brass monkey.  And, now you know the rest of the story.

I wonder how many brass monkeys are losing their balls tonight in this current cold snap.