freeze the balls off a brass monkey

The phrase "freeze the balls off a brass monkey" is an idiomatic expression used to describe extremely cold weather conditions. It is believed to originate from naval terminology, where a "brass monkey" referred to a brass plate or triangle used to stack cannonballs on ships. In cold temperatures, the contraction and expansion of metal caused the brass implement (the "monkey") to contract more than the iron cannonballs, which could lead to the balls falling off due to the increased space between them. Over time, the phrase evolved to describe cold weather that is cold enough to cause objects to freeze or break.