Halo 3 Easter Egg - Marine Locks Himself in the Armory (Brute Buddies)

In the beginning of the level "Crow's Nest" in the chapter titled "Know Your Role..." there is an egg related to a semi-hidden conversation. When walking in the corridor where you'll be fighting the Convenant among many vehicles and such you'll eventually come to an area where you are to turn left to defend the spaceport.

Instead of immediately going through that door continue straight until the corridor curves left and then right. On your immediate right in this dead-end you'll see a Marine banging on a steel door, arguing with another Marine. The Marine that's locked himself in this armory is scared because he thinks that the other Marine is either a Brute or is being held captive by Brutes. Their hilarious conversation happens two different ways at different times (apparently randomly). The first is just a conversation about not trusting him and the second is about the Marine not trusting Master Chief either.

I'll post a picture of the area as soon as the egg is accepted.