Personalized Caffeine Powers Activate T-Shirt. Caffeine Powers Activate! If your super powers take a cup or two (or five) of coffee to show up, then you have caffeine powers! Funny gift for any coffee lover. 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.