I looked at a couple more articles, and they generally go with the "slug = nickel" theory as to the name's origin. The official
Slugburger Festival website (not updated in several years) gave several possible name origins:
I always wonder if those articles are pulling from the same source, so it propagates like how Gamergaters elected Trump
Outside of burgers I've heard of slug as a bogus coin, but I can't find anything outside of burger articles that describe a nickel= slug (not saying it isn't, just saying I couldn't find any in my whole minutes of searching, but I think it makes a good test to go outside of the one context)
Weird though, looks like it can mean a dollar as well.
But maybe the burgers were so shitty that it's sort of a joke. Like this burger is the el cheapo so you don't even have to pay with real money . Like saying it's work $5oo...in monopoly money
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neither here nor there, so hit me with the autism tag!
Just doing lookup b/c no work possible today : but when I looked I hit on plug nickel, I'd always heard that term, but never knew the literal basis
https://en.wiktionary.org/wiki/plug_nickel -- it's a wiki so grain of salt
Oh I did find this cool pic of slugs from a payphone
Check out the top ones, they have strings attached to pull them back out. You sometimes see that in old cartoons
BTW the reason the real coins are considered slugs is they are lower value foreign coins mimicking higher value US coins. The red and green things are tiddleywinks
update :
check this out. I didn't realize the phone company had special test coins with no cash value
BTW, I'm bored as shit