WARNING!!! !!!History lesson coming up !!!!! Brass monkey............or to put it in the correct contect "To freeze the balls off of a brass monkey." A "Brass Monkey" was a brass triangle that was used on old british warships. It was nailed to the dexk and cannon balls were stacked on the "brass monkey" to stop them rolling about the deck of the ship. they were stacked like this:- ^ ^ ^ ^ ^ ^ In very cold conditions the brass triangle would shrink and the triangle would contract, making the balls collapse and roll around the ship.