this is the code
http://www.halo3planet.com/halo-3-skull-locations/iwhbyd-skull/
and this is the secret effect
Marines shout “For Spartaaaa!” as a battlecry. (can be found on youtube)
Brutes say, “We don’t take mastercard”.
Grunts exclaim, “I’m alive? This game rules!“
We got a Futurama fan at Bungie apparently, “Your pending for a bending.“
In the opening cut scenes, Sgt. Johnson says, “Maybe they love the smell of *his cigar name* yeah, I do a little product placement. I gotta get payed too.”