The origin of the word is uncertain. One theory suggests the name is derived from the "gee-dunk" sound which vending machines installed there made when operated. Another theory is that the term is derived from the comic strip Harold Teen, in which Harold eats Gedunk sundaes at the local soda shop.
The gedunk bar was usually open for longer hours than the mess. Such bars were stocked with a wide variety of consumables, such as snacks, soft drinks and fresh coffee.One may also find ship or command items in the geedunk. Such items include ballcaps, shirts, coins and patches that bear the insignia of the unit. In the bigger ships such as heavy cruisers and escort carriers, or battleships and fleet carriers, the gedunk bar also had several flavors of hard and soft ice cream made aboard ship.
In the 21st century, Sailors and Marines continue to call a place where snacks are for sale a "gedunk bar" or "gedunk machine" and refer to the snacks themselves as "gedunk".
During the Vietnam War everyone who served in the Navy got a National Defense medal. Because these medals were issued regardless of any service beyond making it through bootcamp, it was called a Gedunk medal.