Very interesting!
Here's one:
The phrase "Cold enough to freeze the balls off a brass monkey"?
"Brass monkey" refers to the one-piece, berm-type perimeters on the decks of old fighting ships which served to "store" a pyramidal stack of cannonballs.
As these were forged of brass, their expansion/contraction rates differed substantially from that of the cannonballs; extremely cold weather thus resulted in "loose" ammo rolling about the decks.
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