A stinger is a home-made immersion device for using electricity to heat water. It is considered contraband, often as “dangerous” contraband.
It is made by connecting metal plates to each wire of an electrical cord (usually from radio or TV), and keeping them separated by an insulator. They can be purchased for about $5, or made from scavenged parts.
Typically, the plates are made from the blades of disposable razors*(1), and as such should be used to heat a double boiler, or risk consuming toxic metals.
(1) Used disposable razors must be exchanged for new ones. Often, they are visually inspected to ensure the blade is still present. To obtain blades for making stingers or just general cutting, carefully use the thick end tine of a plastic comb to pry the topmost plastic cover from the razor. Remove blade and cut an equal sized section of chrome from a magazine photo of a car, and use it to replace the blade. Re-assemble razor with the new chrome-colored paper blade.