Skull hunting anyone?

[freddy]

does any one know how the 13th Skull is obtained that unlocks that cool samurai helmet for master cheif? and wants to help me get it? =p?

[Shadu]

Man, I still haven't found my first skull...And If I had XBOX Live I'd love to help you get that skull....and I think after you obtain all of the skulls, you're gonna get a Hayabusa armor.

I think they did that to say thanks for getting a spartan on DOA 4.