-30 votes would be extremely unusual on SO. That amount of votes even including upvotes in such a short time would be almost impossible. The only way you get that kind of massive voting is either if the question hits the "Hot Network Questions" or if an external site like HN with a high population of SO users links to it and drives lots of traffic. Questions with a negative score won't hit the hot network questions, so it seems very unlikely to me that it could be voted on that much.
You can get +30 from the HNQ list, but -30 is much harder, because the association bonus only gives you 101 rep, and the threshold for downvoting is 125.
