chalk
n.— « The following information is placed on a 3×5 inch index card and handed to the pilot by the chalk leader. This serves as a contract between the pilot and the chalk of soldiers to ensure coordination of LZ data. In case the chalk lands in a different LZ, the pilot will write the grid of the new LZ and hand the 3×5 card back to the chalk leader before the soldiers exit the helicopter.» —by Dept. of Army 101st Airborne Division (Air Assault) Gold Book (Fort Campbell, Ky.) Feb. 4, 1999. (source: Double-Tongued Dictionary)
Further reading
Is there such a thing as a “neutral” accent, and if so what does it sound like? And that quirk in the way southern Californians talk about freeways. They’ll say things like take the 405 and get on the 8. Why the definite article...
Floordrobe is the new word for an old habit: piling your clothes on the floor instead of putting them away. The Oxford English Dictionary recently added an entry for it, defining floordrobe as “an untidy heap of discarded clothing left on the floor...