The Potato Sack is the name of an alternate reality game (ARG) created by the Valve Corporation and the developers of thirteen independent video games to promote the release of Valve's title, Portal 2, in April 2011. Valve president Gabe Newell envisioned the game as a "Cross Game Design Event" in December 2010, and allowed the developers a free rein to design the game using Valve's Portal intellectual property. The game, requiring players to find and solve a number of puzzles hidden within updates of the thirteen games, ultimately led to the opportunity for players to release Portal 2 about 10 hours earlier than its planned release by playing games under the pretense of powering up GLaDOS, the sentient computer antagonist from Portal 2. The ARG's theme of potatoes is based on plot elements within Portal 2, specifically that for part of the game, GLaDOS's personality module is run off a potato battery.

A gunny sack, also known as a "gunny shoe", is an inexpensive bag made of hessian (burlap) usually formed from jute or other natural fibers, although modern sacks are often made from polypropylene; the "gunny" portion of the name ultimately descends from tulu(Indian Language spoken in Mangalore) goni, "thread, fiber", by way of imperial British corruption of that word's descendants in later Indian languages. Gunny sacks are traditionally used for transporting grains, potatoes, and other agricultural products. Today they are also sometimes used as sandbags for erosion control. Gunny sacks are also popular in the traditional children's game of sack racing.