Red underwear is the garment commonly worn in Italy as a New Year's Eve good-luck tradition.
The custom is associated with love, vitality, and good fortune. People may wear red underwear on the night of December 31, sometimes following a belief that it should be new or received as a gift. As with many holiday customs, practice varies by family and region, and it is often followed playfully rather than as a strict religious observance.
Italian New Year celebrations also include festive dinners, fireworks, and foods linked with prosperity. Lentils are frequently served because their small, round shape resembles coins, while cotechino or zampone may accompany them in traditional meals. These food customs are separate from the clothing tradition, even though both are associated with luck.
The red-garment practice is sometimes reported across other parts of southern Europe and Latin America, but the Italian version is especially well known in popular accounts of Capodanno. It refers specifically to underwear, not simply any red accessory.