Personalized Yay! 21 Fun White T-Shirt. Yay! 21 and ready for fun in white text in a decorative white swirl is a fun design for friends and family at birthday time. Everyone loves our Custom T-Shirts! Wardrobe essential for looking good, 24/7. 5.0 oz., pre-shrunk 100% cotton. Seamless 1x1 rib collar. Shoulder-to-shoulder taping. Double-needle stitched sleeves, bottom hem and front neck. Note: greys are a cotton/polyester blend.