A Gedunk bar or "geedunk bar" is the cantine or snack bar of a large vessel of the United States Navy. The term was popular during World War II. The gedunk bar was usually open for longer hours than the mess. The name is supposed to come from the "gee-dunk" sound the vending machines installed there would make, when operated.

The bar had all kinds of consumables, such as cigarettes and pop drinks and abundant quantites of fresh coffee. In the bigger ships such as heavy cruisers and escort carriers, or battleships and large carriers, the gedunk bar also had several flavors of hard and soft ice cream, made right onboard.

Several museum ships such as the USS Salem (CA-139) have recreated or restored gedunk bars, complete with examples of period dry goods.