Along the same lines of Jim's.... In the heyday of sailing ships, all war ships and many freighters carried iron cannons. Those cannons fired round iron cannon balls. It was necessary to keep a good supply near the cannon. However, how to prevent them from rolling about the deck? The best storage method devised was a square-based pyramid with one ball on top, resting on four resting on nine, which rested on sixteen. Thus, a supply of 30 cannon balls could be stacked in a small area right next to the cannon. There was only one problem...how to prevent the bottom layer from sliding or rolling from under the others. The solution was a metal plate called a 'Monkey' with 16 round indentations. However, if this plate were made of iron, the iron balls would quickly rust to it. The solution to the rusting problem was to make 'Brass Monkeys.' Few landlubbers realize that brass contracts much more and much faster than iron when chilled. Consequently, when the temperature dropped too far, the brass indentations would shrink so much that the iron cannonballs would come right off the monkey. Thus, it was quite literally, 'Cold enough to freeze the balls off a brass monkey.' (All this time, you thought that was an improper expression, didn't you.)

I always thought it was related to music: [Chuck] Brown didn’t just invent go-go, says Johnson, he reinvented what dance bands do. “It’s non-stop. We go from one song to the next to the next – there’s no break,” he says. That’s where the name go-go derives – it’s music with a beat that just goes and goes. Percussive solos are its signature – conga drums, cowbells, timbales, anything with a beat. These transitions between songs turn into crescendos that keep the dance floor buzzing. “That was Brown’s genius,” says Johnson. https://www.theguardian.com/us-news/2019/dec/14/washington-dc-go-go-music-hits-back-gentrification-sould-of-a-city

Same idea but wiki says the practice came from Spain in the early 16th century Red tape

Stacey_mb I worked in a government library, and didn't know the formal definition of a white paper until now! ETA: name.