The decorative seating and tables along the Sugar Tongue illustrate several nautical phrases. Fittingly, this one illustrates the phrase "Freeze the balls of a brass monkey".
Some people believe this comes from the practice of piling cannon balls up into a pyramid (see next picture) and that the brass square used to keep them in place at the base was known as a monkey. Either the brass contracted more than the steel balls causing the balls to pop out and roll across the deck "freezing the balls off" or if the weather was cold enough to freeze the salt water the balls would stick together "freezing the balls of a brass monkey". The monkey doesn't look too sure and with good reason. There is no evidence that balls were piled up on ship as the rocking of the ship would tip them off and the actual physics of expansion eliminates the first effect. In the Royal Navy balls were stored below decks and put on deck on planks of wood with holes in them known as shot garlands.
Other explanations are that there was a cannon called a brass monkey, that the pawn broker's sign might have been called that or simply that the three wise monkey's are often cast in brass and were very popular and thus brass monkey became a useful metaphor for a non-living, inanimate creature. This would explain other phrases such as cheeky as a brass monkey or hot enough to singe the hair on a brass monkey.