Snopes says it was never a food-service term. Some quibble about what it originally meant.
*Some *quibble? Megagigas of quibble, you mean.
Here’s the Cecil column. He also prefers the rhyming slang origin but then talks only about other food-service codes, as if 86 entered that slang as a rhyming term. How is that supposed to work?
If 86 is rhyming slang, then it needs to be a part of a larger vocabulary of rhyming slang. I know of none. A search for American rhyming slang brings up little but hits on Cockney rhyming slang. Subtract hits that include Cockney and the rest feature Australian rhyming slang. Nix on that.
I’d say I’m skeptical of that answer, but the reality is that I flat out disbelieve it.
From the column:
We used more military terminology: “Bogey 4 o’clock!”
RR
A restaurant I worked at decades ago had an “order caller” in front of the kitchen. His call of “T-bone, rare”, an item the restaurant didn’t serve, was what they used.
J.
I could conjecture a connection to “23”, meaning “scram” (later “23 skidoo”), but it would only be conjecture. Still, “23”'s origins are equally obscure as “86”'s.
Still, it seems there was a fad going 'round around the turn of the 20th Century, particularly in NYC, of using numbers as slang. It’s possible – maybe even likely – that they were just chosen arbitrarily.
Powers &8^]