The subject of this article is a product that has been mentioned "in-universe" in a canon source. The HDM Wiki is written from the perspective that all information presented in canon is true (e.g. Lyra's world really exists); as such, details contained in this article may differ from real world facts.
Popcorn was a unique variety of corn which had hard kernels that swelled and burst open when heated. It was often consumed at cinemas.