Did you know this saying is over a century old? I didn't, not until I went to a mining museum that had several old steam engines with ball governors. When the engine runs, the balls spin, and the faster they spin, the more centripetal force, and the balls spin wider. Heading towards the walls. So the faster you go, the balls go closer to the wall.
I'd always assumed the saying had a dirty connotation, and was modern. It's still later than my regency historical novels, but if I ever write Victorian era, I'm totally using this in a book. You really can learn something new every day. :)