It's a secret to most people
Goron mask necklace [found here]
While we're on the subject of all things Zelda, this necklace could totally pass. It's a little on the obscure side -- the Goron mask will be recognizable to Zelda aficionados, but with anyone else, you can probably just pass it off as something as generically "tribal" as your roommate's armband tattoo. This way, it's like secret code.