Pogs are small cardboard discs used in a game of the same name which was very popular in the early 1990s in the United States. Pogs typically have an image on one side, and are either plain or simply patterned on the other. They look remarkably like the cardboard inserts used in milk caps, because the earliest pogs actually were milk caps; the game was developed by bored workers who had a surplus of milk caps to play with.
The game appears to have developed in Hawaii during the 1920s, and according to popular myth, it was developed by employees of a dairy who were looking for something to do on breaks. Allegedly, the name is derived from an acronym for a popular type of juice: passionfruit, orange, guava. This juice was provided in glass jars, much like milk, and the caps were readily available to people of all ages.
When the game caught on on the mainland, several game companies started producing pogs for people to collect, trade, and play with. The increased awareness of the game led to some dispute over its origins. A Japanese card game, menko, is remarkably similar to pogs, and some people have suggested that since pogs originated in Hawaii, the game was probably heavily influenced by this Japanese game.
The game starts with the players deciding whether or not they are playing for keeps. In a game where people play for keeps, they keep the pogs that they win during the course of the game. Once this decision has been made, the players make a stack of pogs; each player is supposed to contribute an equal number, keeping the game fair.
Using a larger heavier disc called a slammer, the first player hits the stack, causing it to scatter. Every pog which lands face-up is won by this player, and taken out of play. The pogs are re-stacked for the next person, who repeats the process. The game is over when all of the pogs have been taken out of play. In a game where players are not playing for keeps, each player gives back pogs belonging to others.
Many children grew very fond of pogs since the pieces were relatively cheap, allowing people with limited income to play the game. However, the game raised issues for school districts, since some children had a difficult time with the competition of the game. Several schools actually banned pogs during the heat of the game's craze, out of concern for academic performance.