Knixwear: Oh-No Proof Underwear. Believing that teens already have enough stress, Knixwear developed a version of their popular leak-proof undies especially for teens. To launch it, we created the Knixteen brand, the packaging (including a re-usable pouch that doubles as a heating pad) and a series of videos that show periods interrupting teens at the worst possible moments. Their message? Knixteen gives girls the confidence to tell their periods to Shut Up!