Why are we playing this game?

Bruce Schneier, one of the most respected voices regarding security, is a troublemaker. I mean that in a good way. In an effort to showcase the reactionary absurdity of airport security today, he is running another Movie-Plot Threat contest. I'll let Bruce explain:

"We all know that a good plot to blow up an airplane will cause the banning, or at least screening, of something innocuous. If you stop and think about it, it's a stupid response. We screened for guns and bombs, so the terrorists used box cutters. We took away box cutters and small knives, so they hid explosives in their shoes. We started screening shoes, so they planned to use liquids. We now confiscate liquids (even though experts agree the plot was implausible)...and they're going to do something else. We can't win this game, so why are we playing? Well, we are playing. And now you can, too. Your goal: invent a terrorist plot to hijack or blow up an airplane with a commonly carried item as a key component. The component should be so critical to the plot that the TSA will have no choice but to ban the item once the plot is uncovered. I want to see a plot horrific and ridiculous, but just plausible enough to take seriously. Make the TSA ban wristwatches. Or laptop computers. Or polyester. Or zippers over three inches long. You get the idea."