People in Spain traditionally eat grapes one at a time during the twelve midnight chimes on New Year's Eve.
The custom is known as las doce uvas de la suerte, or “the twelve grapes of luck.” Participants try to eat one grape with each of the twelve clock chimes at midnight. The grapes are said to represent the twelve months of the coming year, and completing the ritual is associated with good fortune.
The practice became especially prominent in Spain in the early twentieth century. One commonly repeated explanation links its spread to a surplus grape harvest in 1909, when producers promoted the idea as a way to sell excess grapes. The exact origin is discussed by historians, but the tradition itself is firmly established.
Television broadcasts often synchronize the country’s celebrations with the clock at Madrid’s Puerta del Sol. The fast pace can make the ritual surprisingly difficult, so supermarkets commonly sell prepared packs of twelve grapes before New Year's Eve.