With fictional worlds come fictional alcohol. But not just alcohol that's bad for you in the usual ways — bad for you in the "this will kill you if you drink it" kind of ways. These are drinks bartenders need hazmat suits to prepare and serve.
These are not just the drinks that are part of regular worldbuilding. These are the drinks that stories use to prove to the badass bona fides of our characters. Or to provide light-hearted moments of comedy as they drink and then nearly die. Here they are, arranged in rough lethality order.
Pan Galactic Gargle Blaster from Hitchhiker's Guide to Galaxy
Not the most dangerous drink out there, but one that has become the go-to description of an out-of-this-world drink that is strong on a mythical scale. Given the opportunity, you should definitely not drink too many of. While the knock-off Earth version isn't exactly healthy, Hitchhiker's Guide to the Galaxy describes the real stuff as "like having your brains smashed out with a slice of lemon wrapped round a large gold brick." The TV show made clear that you should never drink more than two of these unless you are "a thirty ton mega elephant with bronchial pneumonia."
Aldebaran Ale from Star Trek
While the official drink of Starfleet appears to be synthehol, an alcohol substitute which has none of the bad effects of real alcohol, the Star Trek universe itself has a pile of fictional drinks that could knock you for a loop very easily. There's Klingon Bloodwine, which is barely tolerable by humans. There's a nectar that knocked out Enterprise crewmembers in The Animated series that was compared in strength to Saurian brandy. Quark once tried to serve Doctor Bashir a drink called the "warp core breach," one sip of which would relax him for three days. And then there's the infamous Romulan Ale, a bright blue — and very potent — alcohol that is illegal in the Federation.
But on the scale of flat-out dangerous, Aldebaran whiskey probably wins. It's probably the drink that Scotty uses to win a drinking contest against one member of a crew taking over the Enterprise in "By Any Other Name." Scotty describes it to his unsuspecting victim as "It's green."
The drink got another shout-out in The Next Generation's "Relics," where Data, faced with the same drink, was also only able to describe it as "green." Any time a drink is indescribable? It's probably a bad choice
"The stuff where you get your eyesight back in two days — guaranteed." Red Dwarf, "Gunman of the Apocalypse"
Don't drink anything with that as a selling point. Although Kryten's description does indicate that there's worse out there. Don't drink that either.
Bor'Kaan from Babylon 5
A very potent Drazi alcohol that can only be drunk by humans after taking an alcohol blocker. Which sounds like it takes all the fun out of drinking. A non-lethal version was named for Susan Ivanova and made by diluting it with vodka.
Black Frost from Buffy the Vampire Slayer
In "Beer Bad," a bar owner fed-up with college students acting like class-A dicks brews up supernatural beer that turns drinkers in Neanderthals. Now that is a side effect no one expects when they go out drinking.
Dune Battle of Corrrin Cover Art by Stephen Youll
Spice Beer from Dune
Spice melange from Dune is a miraculous thing. It gives long life, vitality, and heightened awareness and even prescience in some. It's the thing that makes space travel in this universe necessary. So of course it's been added to beer. That's a horrible choice. Why not make this expensive drug that is practically the basis for society into a beer, adding addiction and deadly withdrawal to the usual side effects of alcohol.
Scumble from Discworld
First, should you find yourself on the Disc, avoid any drink that's explicitly for trolls — they have a very different physiology, meaning that one of their drinks is literally a battery that shorts out their silicon brains. But, for humanoids, scumble is the drink to avoid.
It's a drink that's served in thimbles. It can't be watered down since it explodes when it comes into contact with water. Nanny Ogg's version is called "Suicider," and it's not a fanciful name — it's a description of the people who choose to drink it. It's made from "mainly apples," but has "some qualities of fresh apples and some of dimethyl hydrazine before liftoff." We'll leave you with this description from Mort:
A lot of stories are told about scumble, and how it is made out on the damp marshes, according to ancient recipes passed down rather unsteadily from father to son. It's not true about the rats, or the snakes' heads, or the lead shot. The one about the dead sheep is a complete fabrication. We can lay to rest all the variants of the one about the trouser button. But the one about not letting it come into contact with metal is absolutely true…"Scumble is a drink first introduced in the Discworld novel, Mort