Anybody ever heard of this?

fido -- a coin having a minting error (from freaks + irregulars + defects + oddities)

yes.

-ron (it's in M-W 10th) obvious

So it is! 1967 origin. Thanks. But why would coins be termed freaks? That just sounds, um, well, freakish to me.
Is fido ever applied to other things? A misprinted stamp, or something?

>A misprinted stamp..

I tried to unearth such a word, but I think that the philatelists just call a misprint an error.
-joe (how droll) friday

I've been a numismatist all my life. never heard of fido in that application. The preferred term I've always used and heard is mint error.

As far as Fido being a traditional name for a dog...how'd that happen?

BTW, for folks so inclined, something to look for in today's pocket change...the US Maine state quarter is the lowest mintage of them all, and the one to save. Along with the New Jersey quarter because this is the only coin ever minted in US history with George Washington on both the obverse and reverse.

I'm guessing 'Fido' is a good name for a dog because it comes from the same root as 'faithful'. One of our scholars here can surely expound (nah, there *really wasn't a pun there till I proofread).

http://www.usmint.gov/index.cfm?flash=yes
There is a search button where you can look for the errors.

Ah! Fido for faithful! (fidelity) That's terrific thinking, AnnaS. And how interesting that, if your guess is right, that a fido for a bad penny would be one that wasn't faithful to design, not that the roots are the same or anything like that, but I'm just enjoying the differences.


Edit: Must add the onelook.com quick definitions for 'fidelity', especially since the coin that barks is anything but:

"noun: accuracy with which an electronic system reproduces the sound or image of its input signal
noun: the quality of being faithful