Okay, you're probably not going to see this in your lifetime, but imagine how cool you'll seem when you whip out "matchstick ingestion" as part of the differential diagnosis for hyperkalemia and AKI.
Matchstick heads are comprised of over 50% potassium chlorate (KClO3); it is an oxidizing agent which makes matches flammable and can also be found in many explosives and fireworks. Unfortunately, it also happens to be nephrotoxic. In this interesting case report by Mutlu et al, the authors describe a 21-year-old man who attempted to commit suicide by ingesting 120 matchsticks. When he first presented to the ED, he had a serum potassium of 7.4 with peaked T-waves. The potassium chlorate results in a rapid oxidative destruction of RBCs while also causing methemoglobinemia, and acute renal failure is common. A toxic dose is listed as being 5 grams; the patient in this case report only ingested 2 grams was fortunately treated successfully using acute potassium-lowering therapy and hyperbaric oxygen therapy (for the methemoglobinemia).