You finish Metal Gear Solid 4, you get access to a screen where you can enter passwords. Indeed, we've shown you some of these before! These are just like those. If you visit the extras menu, go to passwords and enter jmsotsynrn, you'll get the Type 17 pistol. Nice enough, but entering aottrykmyn will get you the Snake-dressed-as-Altair costume that left the internet scratching its head a few months back. It even matches his moustache!