Karsk is a Scandinavian drink of equal parts hot coffee and clear spirit: six centiliters of pure alcohol such as Everclear, vodka, or homemade moonshine, matched with six centiliters of coffee that must be heated but never boiled. Purists insist on moonshine because it has no flavor of its own and leaves the coffee in front, a claim the episode questions. The drink was popular in a rural Swedish district in the early 1800s, spread through rural Norway in the second half of the century, and takes its name from an Old Norse word meaning healthy, vigorous, or agile, fitting a hot, caffeinated, alcoholic tonic for farm work through freezing winters.

Today karsk is most firmly rooted in Norway’s Trondelag region, among city and country people alike. Cross country skier Petter Northug and musician Bjarne Brondbo are known fans, and former culture minister Trond Giske has said that everyone who grew up in Trondelag has had karsk at some point. Beyond Trondelag the names multiply, and sugar splits drinkers: some regional names refer specifically to the sweetened version, which purists see as masking the burn of the spirit.

• In Hedmark and Oppland, merged into Innlandet in 2020, it is called coffee doctor or by a dialect word for a jack or knave.
• In Sweden it is kask or kaffekask, drunk mostly in the central and northern parts of the country.
• Denmark’s kaffepunch swaps the moonshine for schnapps.
• In English speaking countries the vodka version is sometimes called Russian coffee, a name that can also mean coffee with whipped cream.
• Boiling the coffee is avoided because bitter, overextracted coffee clashes with high proof alcohol.