It's not on the menu. The only hint it exists is a pair of stuffed snowy owls above the bar, perched next to a rack of craft beer bottles.
But if you ask for it by name, the bartender will oblige.
"I haven't made one of these since the last movie," says concessionaire Daniel Moore, as he searches for bottles at Bar 1570 in the lobby of the Tampa Musem of Science and Industry's IMAX Dome Theatre.
He squirts a few shots of butterscotch syrup into a plastic cup. Stirs in a dollop of whipped topping until it's nice and foamy. Adds a shot of Imperial vodka and fills the cup with cheap cream soda.
And presto-chango, expecto patronum: Vodka Butterbeer.
The cocktail is a simple approximation of the butterbeer served at Universal Orlando's Wizarding World of Harry Potter, charmed with a splash of grown-up wizardry. It is a rich, buttery, extremely sweet — and, if we're being honest, not especially strong — cocktail. It costs $6.50; a non-alcoholic version is $4.
MOSI officials say it's the only bar they know of that serves an alcoholic version of Harry Potter's favorite drink. It's certainly the only movie theater where you can order it.
And with Harry Potter and the Deathly Hallows: Part 2 opening Friday, Bar 1570 bartenders are preparing to sling 'em by the dozen.
"We sold a lot of them for the first one, and it makes sense for us to bring it back," said theater director Carl Fullerton. "We don't normally carry whipped cream or the cream soda. But if there's enough of a demand for people, I'll carry it year-round."
J.K. Rowling probably never expected butterbeer to exist in this way. In her books, butterbeer is the casual drink of choice among wizards of all ages, though it can have mildly intoxicating effects. In Harry Potter and the Prisoner of Azkaban, it is served warm, and Harry considers it "the most delicious thing he'd ever tasted."
When the Wizarding World of Harry Potter opened in 2010, ice cold butterbeer became a reality, and a bit of a cult concoction. Almost any mention of a trip to the theme park sparks the question, "Did you try the butterbeer?" In June, the indie rock group Florence and the Machine was photographed chugging butterbeers outside the park's Hogwarts castle.
Officially, the Wizarding World is the only place to get true butterbeer. But it didn't take long for curious mixologists to start swapping recipes for homebrewed versions online. And MOSI wanted in on the action.
Situated adjacent to the theater's concession stand, Bar 1570 serves sangria, margaritas, specialty cocktails and craft beers, and even more adventurous drinks like absinthe. Prior to Harry Potter and the Deathly Hallows: Part 1, Fullerton visited Universal Orlando to sample the drink and brainstorm outside-the-box cocktail ideas.
"Some of our summer camps and camp-in programs, they've had Harry Potter-themed events in the past, and they've made their own butterbeer," he said. "But no one ever told me how. Well, we've got a bar — why don't we do it?
"We started testing it, and the vodka just slides right in there. You don't even taste it."
Fullerton screened the final Harry Potter film Tuesday, and said there's a scene where some of the characters drink butterbeer. At MOSI, you'll be able to drink right along with them.
If Vodka Butterbeer is a hit this weekend, Fullerton said, it could become a permanent addition to MOSI's drinks menu.
Felix Felicis or Polyjuice Potion may not be far behind.