This bit from Jon Stewart captures my frustration with the lazy way "who could have known about this unanticipated event" arguments are deployed:

"Here's something you always like to see," Stewart says, scanning the front page of the Washington Post. "'U.S. Trade Deficit Startles Markets.' Now, we've understood the U.S. trade deficit for a while. Are the markets small children that are easily startled? The next day, they'll get an unemployment number and go, 'Oh, I don't know why we were startled and lost 200 points yesterday; today, we realized the shirt on the chair wasn't a monster, so we're going to put 300 points back on the Dow because we're fucking 5 years old.'"

Hint: your own stupidity is not a Black Swan. Okay?