Scan the backbar at any half-decent cocktail bar and, among the cut-crystal mixing glasses and obscure liqueurs, you might catch sight of a DIY-looking label adorned with red and blue flames. That’s Rum Fire, a high-ester, overproof rum from Jamaica’s Hampden Estate that’s just as recognized for its MS Paint–quality branding as its palate-scorching funk. And since hitting American shores in 2016, it’s become a favorite oddball tool in the bartender’s arsenal.

“A lot of rums are sledgehammers and a lot of rums are scalpels, and Rum Fire is a sledgehammer,” says Kevin Beary, of Chicago tiki bars Three Dots and a Dash and The Bamboo Room. “When you open a bottle you can smell it across the room, like tropical fruit and overripe banana. The overall characteristic is just really, really bold, but when it’s worked with properly, you end up getting really tasty flavors.”

In part, Rum Fire’s pluck comes from esters—fragrant chemical compounds formed when acids (like acetic and lactic, made by microbes during fermentation) interact with alcohol in the still. When concentrated, esters can emit a range of potent aromas and flavors including sweet fruit, butterscotch, clove and caramel. “In the production of Rum Fire there’s a very long molasses fermentation,” says Beary. “Much longer than you’d see in lighter-bodied rums.”

A 10- to 14-day open-air fermentation isn’t the only way Hampden Estate encourages bacterial growth and thus ester production. The producer also adds heaping doses of dunder, the richly acidic gunk left in the still from previous distillations, and muck, a bacterial stew akin to a boozy sourdough starter, to the wash. In the end, Rum Fire’s ester count weighs in at a whopping 500 to 570 parts per million (for comparison, a dry Cuban rum like Havana Club Silver hovers around 200 ppm).

Located in Trelawny, Hampden Estate dates to the 1700s and is one of only seven Jamaican distilleries still operating, down from 600 in the mid-19th century. Until recently, most of their product was shipped in bulk to European rum blenders while the highest-ester juice went to industrial food flavoring labs. All that remained were illicit jugs of John Crow Batty, a crude high-octane distillate siphoned by distillery workers for their own consumption (its name comes from its unsavory aroma: “John Crow” is a local term for turkey vulture, and “batty” is slang for backside). In 2011, Hampden Estate capitalized on the explosive hooch with Rum Fire, a refined 116-proof version of the bootleg bottlings and the distillery’s first direct-to-market release.

“Rum Fire is an aggressive beast in the best way possible,” says Ray Sakover, head bartender at Times Square tiki bar The Polynesian. Sakover turns to Rum Fire whenever he wants to add complexity to tropical standards like the Trader Vic Mai Tai and classic Daiquiris, as well as modern riffs like the Nuclear Daiquiri.

“To me, Rum Fire stands apart partially in pedigree,” says Marlowe Johnson, beverage director at Detroit’s Flowers of Vietnam, referencing the 266-year-old distillery’s doggedly traditional production process and proven staying power. “Hampden Estate has such a mythical reputation that anything by them is automatically given a stamp of quality.” Johnson uses it to impart a dry, tropical funk to any drink, including his standard Daiquiri formula.

“We use it for its proof, obviously, but at the same time a little bit really boosts the nuances of tiki drinks,” says Beary, who uses a half-ounce in his 1934 Style Zombie, which is served on crushed ice to allow the bold flavor to peek through necessary dilution.

For Alexandra Farrington, who has worked at Guadalajara’s El Gallo Altanero and Oak & Ivy in Las Vegas, Rum Fire was a gateway to more elevated cocktails. “I grew up in a beach bar making Rum Runners and Bahama Mamas,” she says. “When I started revamping the syrupy, low-quality drinks of my young career, I found Rum Fire.” Farrington deploys it in split-base Daiquiris, punches, tiki drinks and even frozen drink machines.

Bartenders can wax poetic about the unlikely hit’s nose-tingling aromas and hallowed terroir, but it’s clear that one of Rum Fire’s biggest selling points remains its hokey label, more akin to something you’d find stuck to a middle schooler’s Trapper Keeper than a top-shelf bottle of booze. “Aside from the prestige of Hampden, I think Rum Fire really captured bartenders’ hearts because of the absolutely bonkers label,” says Johnson. “It just looks like the best kind of trouble.”