So What Was The Rove - Republican October Surprise?

Myblood asks an excellent question, the answer to which I have a couple of possible yet hardly definitive choices.

What do YOU believe was the Rove - GOP October Surprise? Please answer in Comments; I'd love to see what people have to say.

We know they got surprised a few times in October. And strangely, it was on nothing that should have come as a surprise to them whatsoever.