Brad owning 1UP.com during a live stream of the StarCraft II multiplayer beta. And then Bob Colayco shows up...
During their StarCraft II TNT there was a particularly tense fight against a Zerg player who used lots of distraction tactics. The match itself may have been fairly typical but the commentary from the rest of the crew made every move seem awesome, because none of them knew what was going on and started borrowing terms from other competitive video games.
Playing a few rounds of Team Fortress 2 during the Happy Hour one week with Robin, aka Robin Walker, who created the damn game. Even better, one of the guys was playing Medic on BLU and proceeded to heal Robin (who was playing Soldier) during the setup period, and Robin saluted him and said thanks.