Electronic Arts
They'll hear me shout, cheer, and swear just like I would during a real game, so they'll come in to see what all the fuss is about.
They'll watch on for a few seconds, and with a confused expression, they'll ask "Wait, is this a video game?"
Of course, it's just for a moment. They piece it together after they take a closer look and see the tell-tale signs of a video game, like the little colored arrows on top of player heads and the controller in my hands.
Still, for a game to look so good than it momentarily fools people into thinking it's the real thing is quite a feat.