Just insert two AAA batteries into the sewn pack, push the button, turn off the lights, and your friends can stare at your animated shirt all night long. That is, until you kick them out of the room. The dark gray t-shirt is made of 100% cotton and is washable once you remove the animated decal. Currently, sizes M, L, XL, and XXL are available for $24.99 each at ThinkGeek.com. Oh, and make sure you check out the video to see how it works!