"Don't think it's just our world, Sam." Which wasn't something he'd yet admitted aloud, and had only barely admitted to himself. After all, if one lone broken seal was pulling people in from other worlds, and occasionally sending them back, how did they known that the apocalypse here wouldn't spread, like ripples in a pond? The whole of creation could collapse in on itself which was one of the weirdest things he'd ever had to think about.
He sighed then, world-weary and exhausted in a way he so rarely was. He dug in his pocket for a moment, coming up with a keyring and taking a moment to detach one of the loops, tossing the key in a high arc to Sam, nodding towards the far end of the yard, "Rover's got about a half tank." He shook his head then, "Finish this thing boy, and don't make me regret this."