During a Hackmaster campaign, a particular bar requires first-time patrons to order Gut Busters. They use it to weed out low-level characters; drinking a drink of it does 1d10 damage, which is more than most first-level characters have. Bob's character, after being assaulted by certain patrons, gets a double, forgetting both that he's been injured and that each shot does 1d10 damage. He dies from the drink, to the shame of his party members.
Mojo Dave's "mojo juice" apparently has this effect in the real world.
Subverted in one old Hägar the Horrible strip: told that "You gotta be tough to drink in this place" at the bar he's frequenting, Hägar downs something that creates the typical effects... but when he asks for a glass of water afterward, the bartender tells him, "That was a glass of our water!"
The Kickapoo Joy Juice from Lil Abner, having been described as "more inflammable than jet fuel".