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If anyone still doubts that they’re potentially being watched online by the U.S. intelligence services, or that those agencies share information with countries that are not supposed to be spying on their own citizens, say hello to a 28-year-old German man named Daniel Bangert.

Bangert made a joke on Facebook(s fb), setting up an event for an NSA spy-spotting walk around the so-called Dagger Complex, a U.S. military installation near Griesheim, south of Frankfurt. The event was described humorously in the terms you might associate with a nature stroll, referring to “the threatened habitat of NSA spies” and so on.

Four days later, the German police showed up on Bangert’s doorstep to question him about his putative “demonstration” and apparently non-existent anarchist links. He denied having any such links or planning any kind of demonstration, but the police told him to get a permit nonetheless. They asked him not to tell anyone online about their visit.

That clearly didn’t work. After the story got reported by a local paper, it eventually made its way to Der Spiegel, which got confirmation from a police spokeswoman that the alarm had been raised by the U.S. Military Police. It seems the U.S. Military Police found Bangert’s Facebook post and alerted the local authorities — hence the visits to his house.

In the end, the interest raised by the story led 70 people to join Bangert’s “NSA safari”, although they apparently didn’t see any spies in their natural habitat.

It’s a story that’s both funny and disturbing. Unless he’s just pulled off a brilliant double-cross with the media, Bangert is not a terrorist — he’s just an ordinary chap who was being sarcastic online. And even if he was being serious, all he was doing was threatening to go for a walk around the perimeter of a so-called top secret facility that’s not actually top secret.

Honestly, if the police hadn’t fessed up I’d think this story had been concocted as a viral case study for the anti-PRISM campaign. But it wasn’t.