Used to describe cold weather, this saying derives from the traditional Navy phrase "cold enough to freeze the balls off a brass monkey". This references the brass structure or 'monkey' where cannon balls were stacked. 'Mad as a hatter'

There's no denying that the Beastie Boys were responsible for popularizing the Brass Monkey, but the origins of the drink are much more mysterious. In fact, the Brass Monkey they were rapping about was not orange juice and beer (or malt liquor), but a canned precursor to Smirnoff Ice.

It was widely and incorrectly believed that the Beastie Boys were referring to a different drink made from a 40-ounce container of malt liquor mixed with orange juice ("forty" is mentioned in the lyrics); however, Mike D has publicly confirmed that the premixed Heublein cocktail was their inspiration.

In the days when gulf wars had more to do with sailing ships than TV coverage, cannon balls were stacked on the decks in pyramids. The pyramids were held in place by a brass frame around the base, called a "monkey". When it got cold, the brass monkey contracted, and the cannon balls rolled off around the ship's deck.