Personalized It's My Birthday T-Shirt. It's My Birthday! A cute little cupcake is dancing with joy because it's your birthday! Cute birthday gift for that special someone! 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.