Personalized Rock On T-Shirt. Rock On. A rock sits atop the word on is a humorous twist to a common phrase. Make your favorite rockers and music lovers smile with a unique gift at birthdays, holidays, graduations and back to school. 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.