Bruce Schneier has posted the semi-finalists in his fifth annual Movie-Plot Threat Contest. A movie-plot threat is any improbable, showy security risk that is used to justify a "security" measure: "What if terrorists decided to put acid in McDonald's Shamrock Shakes? We have to cancel St Patrick's Day!"
Here's my favorite entry this year, "The Boy who Didn't Cry Wolf," by yt:
There was a boy tending the sheep who saw a strange shadow at the edge of the woods. The boy thought it might be a wolf, but he was unsure of what he'd seen and didn't want to cause unnecessary alarm, so he said nothing. The next day the shadow came closer. It really was a wolf, but the boy had kept quiet so there was no one to come to his aid. The whole flock and the boy were eaten by the wolf.
If you see something, say something.
(Image: Do you see something?, a Creative Commons Attribution Share-Alike (2.0) image from tonyb2007's photostream)