When people use certain phrases, do they really know the origins?

For example (for our Mid-West folks - cold as all get out right now), how many use the phrase "Freeze the balls off a brass monkey"?

What is a brass monkey?

In days of sail and simple cannon, by each gun was a tray, indented to hold cannon balls and made of brass.
The cannon balls were stacked neatly layer upon layer into a pyramid.

One of the properties of brass is that it is soft, and will expand and contract according to the ambient Temperature.

When it got very cold, the cannon balls would collapse due to the brass monkey contracting.

Thus - Freezing the Balls off a Brass Monkey.