Y2K shirts refer to a style of shirts that were popular in the late 1990s and early 2000s. During this time, many people, particularly young people, embraced a fashion aesthetic that was flashy, colorful, and bold. Y2K shirts often featured bright colors, patterns, and graphic designs, and were made from a variety of materials, including cotton, polyester, and nylon. Some popular styles of Y2K shirts included T-shirts, tank tops, and halter tops. Y2K shirts were often worn with other types of Y2K clothing, such as jeans, skirts, and jackets, to create a complete outfit.