A friend of mine once told me a story about crossing the U.S.-Mexico border. On their way back from a vacation in Mexico, his family (all U.S. citizens) were going through a security checkpoint when a U.S. border officer asked if they had any questions. "Yeah," replied my friend’s father, "do the flies in the back need green cards?"

Thus ensued an hours-long search of the family’s car.

I was reminded of that story yesterday, when some kid made a joke about terrorism to American Airlines on Twitter. The airline’s account immediately responded that it had reported her IP address to the FBI, and a classic Twitter firestorm followed.

Now this person, a 14-year-old Dutch girl, has reportedly been arrested. This ridiculous overreaction is a classic demonstration of two major problems with the mindset that governs our approach to security: its hair-trigger response to even the least feasible threats, and its total inability to manage risk in a realistic way.

Yes, violent extremists are on social media. But they use it pretty much like anyone else: for organizing, talking amongst themselves, and self-promotion — not for threatening potential targets. That would be, shall we say, tactically unwise. Or maybe I missed the part in the Al Qaeda training manual where it stipulates one should publicly threaten institutional social media accounts before an attack?

American’s reaction — mobilizing the arm of the state against some silly kid — was obviously not driven by a belief that the airline was about to suffer a terrorist attack. Just 30 seconds of investigation would have shown that the very idea is ludicrous. Instead, I'd wager that whoever was running the account was mad that the kid wasn't giving the super-serious issue of terrorism the respect he or she thought it deserved, and issued a retaliatory threat on the company's behalf.

American is just one company. But as my friend’s story shows (and as this poor kid is discovering), duly authorized security officials are, if anything, more prone to this kind of hypersensitivity to perceived disrespect. It’s a problem because, on the one hand, it enables petty tyrannies and abuses under the cover of "keeping us safe." On the other hand, every minute spent investigating obviously frivolous threats — like spending money and time arresting a naive teen — means law enforcement resources that aren’t being spent on actually protecting the public.

We don’t have to take every threat seriously. On the contrary, security experts have demonstrated that one of the keys to effective security is efficient application of resources. Narrowing the field of suspects is a central part of this, which, by the way, is one reason dragnet surveillance is so ineffective.

Sometimes kids say dumb things. But at least we can thank this dumb kid for revealing the absurdities of our counterterrorism apparatus.