Personalized 18th Birthday Party Long Sleeve T-Shirt. 18th Birthday Long Sleeve T-Shirt - White has colorful polka dot number 18 and Time To Party quote on this great bday celebration gift. Pre-shrunk 100% cotton 6.1 ounce long sleeve t-shirt. Double-needle stitched neckline and sleeves. Quarter turned. Shoulder-to-shoulder taping. Adult: S, M, L, XL, 2XL, 3XL