We have to take off our shoes walking through TSA security checkpoints, because Richard Reid’s shoes had wires coming out of them and nobody noticed. And lighters were banned because if Richard Reid had had a lighter he might have been able to light his shoes on fire.
But even the TSA now admits the lighter part is silly. Lighters are safe. At least they will be on August 4th. But as Mike Boyd points out, until midnight on August 3rd they are apparently still dangerous.
At least at some point in the future shampoo may no longer be dangerous. But I won’t count on it.
Update: Upgrade: Travel Better points out just how surreal it is that lighters carrying fluid that’s flammable are ok.. but water is still somehow a security threat.