One of the three1) forms of currency used on Improbable Island. The other two are Requisition Tokens (Req.) and Supporter Points2). Cigarettes (also called cigs) may be consumed (smoked) for a long-lasting buff or (eaten) for a long-lasting stomachache.3)4)

Many necessary items and commodities are sold either with a cigarette component to the price (higher powered weapons and armor; housing, and equipment) or are sold solely for cigarettes (most mounts, or sugar, tea, and coffee at the Trading Post). Improbable Island cigarettes are magical and present absolutely no chance of horrible, long-term, incurable addiction or chronic diseases. See? It says so right on the packet!5)

1)
There is a fourth in the form of cobblestones, but nobody knows what they are used for
2)
Gained by donating organs and body parts to a worthy cause, such as keeping CaveMan Joe and Emily fed.
3)
But don't smoke too many, or you run the risk of a long-lasting negative 'withdrawl' buff. Definitely bad news.
4)
Don't eat too many either, or you run the risk of a long-lasting negative 'withdrawl' stomachache. This is bad news as well.
5)
So why does nicotine gum exist? The world may never know . . .