It's cold enough to freeze the balls off a brass monkey... came from the 18th century British Navy.,,, They had monkeys (square racks made of iron and designed in squares to hold 16 cannon balls). However, when in icy conditions, the iron was subject to shrinkage and the cannon balls rolled off onto the deck. Subsequently, brass monkeys were made which actually worked well..... but the expression, it's enough to freeze the balls off a brass monkey was coined.