In the “The Simpsons” universe, if someone is talking about beer, they’re definitely talking about Duff. In the 750 (and counting) episodes of the Fox Network animated series, fictional beer brand Duff (along with its countless iterations like Duffenbraü and Duff Stout) is the official brew of the TV show. Its ubiquitous logo — a large D and a coy U sitting on a see-saw-like slash connecting two F’s — and simplistic can art are reminiscent of many real-life American macro lagers. Even the brand’s name adds to its realistic tilt: Duff is a sexless word that mimics the phonetics of any monosyllabic macro lager like Bud, Coors, or Schlitz. And even though the creators of “The Simpsons” never planned on bringing Duff to the 3D realm, a number of breweries have done just that over the years.

Since the show’s premiere in 1989, the world has seen the rise and fall — and, in some cases, full-fledged legitimacy — of lagers called Duff Beer, all designed to tug at the heart strings of nostalgic millennials whether or not the beer mentions “The Simpsons” in its advertising. In fact, most of these brands have specifically avoided doing so to keep 20th Century Fox from slamming them with lawsuits, which has happened time and time again. Simpsons creator Matt Groening has been quoted saying that he avoided bringing Duff Beer to the real beverage market as he feared that it would encourage underage drinking, but that didn’t stop a slew of bootleggers from doing it for him. Duff Beer is legally considered Fox’s intellectual property, but when a product is rooted in fiction, copyright laws around said product become a bit iffy. That gray area has given the various Duff manufacturers some wiggle room to operate.

The True(ish) Duffs

The first Duff knockoffs weren’t actually knockoffs to begin with. In 1992, New Zealand’s Duff’s Brewery (named after co-owner Gavin Duff) was founded and began pumping out branded Duff’s Brewery beer. Even though its beer drew zero inspiration from the American series, the brewery rebranded as McDuffs after 20th Century Fox hit them with a lawsuit. Not long after, Australia’s Lion Nathan Brewery also made a Duff beer, and the network again made quick work to eradicate the brand. The resulting legal battle ended with all units getting pulled from liquor store shelves and destroyed. Over in England, Daleside Brewery also began producing a Duff beer, deriving its name from the Gaelic word “dubh” which translates to “dark.” Fox left Daleside alone, but the brewery has since ceased production.

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Duff Takes Europe

Come the early aughts, flagrant “Simpsons” imitations were brewing overseas. Germany’s Duff Beer GmbH acquired trademark rights to the name in 1999 and began rolling out its take on Duff Beer. Shortly after, a separate entity called Duff Beer UG secured a simultaneous trademark and contracted Hessen brewery Eschweger Klosterbrauerei to produce the Legendary Duff Beer, though both brands entirely neglected to mention the show in their advertising. Fox made attempts to try to squash the German rip-offs by applying for an E.U. trademark to use Duff Beer to sell non-beer Simpsons merchandise overseas — like sodas and energy drinks — but that was delayed and eventually shot down on the grounds that selling non-beer items as Duff Beer would be misleading.

Fox finally acquired the German Duff Beer trademark in 2014, but both German brands still continue to produce and sell their brews in a few international markets, though any websites claiming to link to the German entities are defunct. There’s even a Duff-themed sports bar in Albania that’s been able to avoid legal troubles to this day.

Duff in the South

Central and South American countries have had a similar saga with unsanctioned versions of the lager. In 2006, Rodrigo Contreras acquired a trademark for Duff Beer in Mexico, and began selling it in a can identical to the one shown on TV. The beer made its way to other Latin American countries before Fox made a few feeble attempts to eradicate it. In 2013, Chilean police seized around 60,000 bottles of the stuff, but that did little to slow Duff Beer’s Latin American production. Contreras’s own Simpson’s Brewing Company in Tijuana still operates under a low profile. Colombian brewery 3 Cordilleras produced a Duff Beer for a few years, and Argentina’s Bierlife did the same. Due to the prevalence of South American Duff knockoffs, Fox decided to stop trying to weed out imitators in 2015 and instead collaborated with Chilean beverage producer EMSA Chile to start brewing officially licensed Duff Beer for the Chilean market.

Domestic Duffs

Despite the international takeoff of faux Duffs, U.S. attempts to copycat the brand haven’t seen the same success. Bilbo’s Pizzeria and Brewery in Kalamazoo, Mich., served its own short-lived version complete with a custom Homer Simpson tap handle, but it was discontinued not long after its inception. The only glimmer of hope for American “Simpsons” fans came in June 2013 when Florida’s Universal Studios began offering officially licensed Duff at the theme park’s Springfield area, where guests can patronize a real-life version of Moe’s Tavern. There, visitors can enjoy three different varieties of the fictional brew: Duff, Duff Lite, and Duff Dry, though if they’re manufactured in the same way the animated series details, all three beers are actually the same suds with different labels. These official Duff Beers are brewed by Carib Brewery USA (formerly Florida Beer Company) in Florida, but distribution has yet to expand beyond the theme park.

Successful or not, the sheer number of attempts to bring Duff to the real world is pretty astounding, and speaks to the lasting, worldwide appeal of “The Simpsons.” What’s inside the can is clearly beside the point — as long as the beverage provides a connection to the classic show, fans will likely flock.