The gas produced by shaking a carbonated beverage is carbon dioxide (CO2). When a carbonated drink is shaken, the pressure within the container increases as the dissolved CO2 gas is released from the liquid. This release forms bubbles that rise to the surface, leading to fizzing. When the can or bottle is opened, the pressure is released, causing the gas to escape rapidly, which can result in the beverage bubbling over. Carbon dioxide is responsible for the effervescence found in fizzy drinks, contributing to their refreshing qualities and enhancing the sensory experience of consuming them.