Gar-bar root

This substance, derived from the root of the gar-bar, a plant believed related to the rubber tree, is sold in most of the larger cities in the planes. Especially common in Sigil, gar-bar root is comparable to both gum and chewing tobacco. This small treat is a rubbery material usually sold in small cubes that, when chewed, produce a strong, almost overpowering sweetness that quickly dulls over time. Gar-bar root is slightly addictive, though controllably so in most people, and is not meant to be swallowed. Though swallowing gar-bar root isn't harmful, nor is it especially comfortable, and it has no true nutritional benefits.

Reference

• Planescape: Torment