my favorite is the password lacking marine Easter egg in halo 3
Easy/Normal Transcript
(listen)
Marine (Jason Saldana, Tucker): Hey, open up!
Voice (Matt Hullum, Doc): Password, please.
Marine: You gotta be kidding me! What password?
Voice: The password so we don't open the door for Brutes.
Marine: Do I sound like a Brute to you?!
Voice: Well, you could be held prisoner by Brutes.
Marine: If I was held prisoner by Brutes and knew the password, then the Brutes could just force me to tell you the password and you'd open the door for them.
[Brief pause]
Voice: Okay, well now I'm definitely not gonna open the door.
Marine: But we need ammo!
Voice: Well why don't you go ask your Brute buddies, then?
[Continuous Knocking].
Heroic Transcript
Marine (Gustavo Sorola, Simmons): Hey, open up!
Voice (Geoff Ramsey, Grif): Password.
Marine: What?
Voice: Need the password!
Marine: You gotta be kidding me! What password?
Voice: Password! They gave it out at the staff meeting fifteen minutes ago!
Marine: Meeting? What meeting?! I was out here!
Voice: Not supposed to let anyone in without it.
Marine: If the staff meeting just ended, no one outside is gonna know the freakin' password! Now open up! We need ammo and the Chief is out here!
[Brief pause]
Voice: Does he know the password?
Marine: He wasn't at the meeting either!
[Continuous Knocking].
Legendary Transcript
(listen)
Marine (Burnie Burns, Church): Hey! Open up!
Voice (Joel Heyman, Caboose): What's the password?
Marine: Password? Oh man, I forgot.
Voice: Forgot... what?
Marine: I forgot the password.
Voice: See, that was almost right. Uh, see, the password begins with "I forgot", but ends differently. Um, try again.
Marine: No. I mean, I forgot the password.
Voice: No, okay, see, you - you got it wrong again. See, you said the same thing as last time.
[Brief pause]
Marine: *sigh* I'm being serious; I don't know the password!
Voice: No no no, see, you changed the first part. See, that - that part was the right part. See, now you've got the whole thing wrong!
Marine: No! I forgot what the password is and I just need you to open the door!
[Brief Pause]
Voice: Alright, c'mon, man, now you're just guessing!
[Continuous Knocking].