This is too cool to pass up. I even did a page on this at mahalo.com a while ago but didn't realize it was post-worthy.
Here's how you do it. Play as Snake on Shadow Moses Island against whoever. When the match starts push down on the D-pad (sickeningly fast) to trigger the codec conversations. I've heard "push down and punch, or punch and down" but no official say on it really. We seemed to get it when doing some sort of rapid seizure movement involving down and a button in some way. Nintendo what's up with that?
Anyway the codec conversations are great. It's funny to hear important military calls about people like Yoshi or Jigglypuff. Or Wario, here's a bit of his:
CAMPBELL: "Wario loves garlic. He eats whole cloves of it day and night, so try not to get caught in his mouth. Once that smell gets on you it'll stick to you for quick a while."
SNAKE: "That's a scary thought."
CAMPBELL: "He also attacks by farting. He can fart to fly around too."
SNAKE: "By farting?! Are you kidding me?!"
CAMPBELL: "Sadly, no. I am not kidding. If his belly starts to bulge, watch out."
And people accuse RPGs of being campy...
Anyway back to RPGs.