Cigarette
From Halopedia, the Halo wiki
Cigarettes are a type of tobacco product manufactured and "smoked" by humans. Cigarettes have been around for hundreds of years, as have their counterpart Cigars, but as of 2552, Cigarettes are apparently far less popular then they once were.
Cigarettes feature individual waterproof seals that protect them from moisture damage, and they also feature "ignition ends" that light up when they are tapped, negating the need for lighters or other fire producing ordinance.
Some ODSTs like to smoke "contraband" cigarettes which do not have ignition ends, instead they use "strike anywhere" matches issued to them by their commanders. This "contraband" monkier may mean that Cigarettes have become largely illegal in 2552 because of their deleterious effects on health.
The only person so far mentioned as a smoker of these is Corporal Harland, although Private Walker accepted one Harland offered him.