I mentioned this in a comment in my main journal, but I figure it's worth recording here as well.
The Clancy Brothers recorded an Ewan MacColl song, "Shoals of Herring," on their album The Boys Won't Leave the Girls Alone. There's a line in the song that I always heard as "with a hundred grand of the silver darlings" (meaning a hundred thousand). But the version of the lyrics posted at Cantaria has it as "a hundred cran."
At first I figured that must be a misprint; MW3 doesn't list the word "cran." But I checked OneLook Dictionary Search, and discovered that "cran" is the standard unit of measure for fresh-caught herring, about 45 gallons.
But how many herring is that? Luckily, itymbi foresaw that we might want to know, and gave an answer a couple years ago. It pointed to the cran page at the very useful (and previously unknown to me) sizes.com, which tells us that a cran can vary from 700 to 2500 herring, but averages around 1200.
So actually, a hundred cran is probably significantly more than a hundred grand of herring.
The sizes.com page also clarifies that it's 45 wine gallons, equal to 37.5 imperial gallons.
Side note: In some sense, this doesn't fit my usual criterion of being a word that I haven't heard before; I've been hearing it since I was a kid. Except I didn't know I'd been hearing it 'til last night, so I figure that's close enough.