..to freeze the balls off a brass monkey!
What a great old British saying that is!
Well, not quite.
Back in the old days of wooden warships, when Britania ruled the waves, and cannon fired iron cannon balls, these balls were stored on racks. These racks were made of brass, and were called Monkeys.
I very cold weather, the iron cannon balls would shrink - shrink more than the brass racks did - allowing them to fall through the racks.
Hence the saying.
Oh well, it is still a good saying.
Now if the saying had been about freezing the balls off a Powder Monkey, things would be different - Powder Monkeys being the young boys who carried the gunpowder from the store room to the cannons...