Banged Grains

The Discworld equivalent of popcorn. A tasteless snack which, if buttered and salted, tasted of salt and butter. Probably the only edible thing invented by the Alchemists, who were also the developers of the moving pictures industry and owners of the Century of the Fruitbat firm. Customers paid a couple of pence to keep themselves entertained chewing them while entranced by watching moving pictures on a giant screen.

Although first seen in the book Moving Pictures, several books earlier the playwright Hwel briefly amends the line:

All the Disc it is but an Theater, Ann alle men and wymmen are but Players.

with

Except Those who selle popcorn.

The fact that the alchemist who invented it implied he had thought of it a while back helps solve this continuity issue, as does Hwel's unfortunate tendency to attract inspiration-particles better suited to other times, places, or realities.