I think the thing that baffles me here is that based on the basic math - 180 minutes, 6000 orders per minute, $15 credit per order - this would seem to be a ~$16M promotion. That's, like, two or three Superbowl ads. For, what? To create chaos? To sow distrust that GrubHub can complete orders? It seems very unlikely here that more people will be delighted by the promotion than frustrated.