From the Department of
Fanciful but Pretty Good Etymology. I see that even
the OED (Oxford English Dictionary) is hazy about
the word “baloney,” in the sense of “humbug” or
Commonly regarded as from Bologna (sausage) but the connection remains conjectural.
I had a Neapolitan—or, at least, southern Italian—explanation all worked out, and it wasn’t bad. It wasn’t true, but it wasn’t bad. It is well-known (according to a local TV station, and why would they lie?) that immigrants to the New World from these parts would commonly smuggle forbidden sausage past customs inspectors by hollowing out large blocks of cheese and stashing the meat in there. Thus, assuming that “baloney” is a cute diminutive from “Bologna” (probably) and if a certain kind of Bologna sausage is a smuggled item, then “baloney” becomes a synonym for “that which is false”. Unfortunately, that well-constructed syllogism is almost certainly low-grade bockwurst, if not downright baloney, since southern Italian immigrants were probably smuggling a totally different kind of meat, and I don’t think you could just roll a huge wheel of cheese past the customs guards, either.
A better explanation is that in the city of Bologna, there used to be a medieval market that traded in phony gold, such that there is a common doggerel proverb in Italian that says:
“L’oro di Bologna/si fa nero per la vergogna”
“Gold from Bologna turns black from shame.”
There is even a common Italian verb, sbolognare—which contains the name of the city—meaning “to get rid of something,” with the implication that the object is, if not worthless, at least not useful. That expression is probably connected with the trade in fool’s gold. Though there is no Italian expression that uses the name “Bologna,” itself, as a synonym for “worthless,” that meaning might have developed as an Italian-Americanism within the immigrant community.
Bologna sausage widely known and spelled elsewhere as "baloney" is really mortadella, a concoction of pork, donkey and wild boar—a mystery meat minced by medieval monks. The mortadella from Bologna was so highly prized that even today in Italy the name of the city is a synonym for the meat. You walk in and buy Bologna. Thus—let’s see how this is doing, so far—Bologna, fool’s gold, mortadella, immigrants—ergo, mortadella (baloney) is a metaphor for that which is not authentic. Also—if you have seen the 1971 film with Sophia Loren, La Mortadella—she tries to walk past the customs station in New York with one very large piece of Bologna, only to be told that “you can’t bring salami into the country”. (In the photo, above, Sophia is the one in the lower right.)
“It’s not salami. It’s mortadella,” she says.
The rest of the film revolves around the almost theologically fine distinction between minced pig, donkey, and boar, and minced whatever-else goes into other things such as salami. I hope I get a nice letter from the OED. And I challenge them to say “mystery meat minced by medieval monks” really fast. Five times.