A far, far deadlier variation of the Köpenick caper: In Norway, 2011, Anders Breivik got himself ferried to the Utøya island solely on the strength of convincing demeanor and a homemade pastiche of a police uniform.

There was a real policeman in charge of security on the island. After the bombing of government headquarters in Oslo an hour earlier, everything was on top terror alert, and Utøya had beeen put in quarantine, the connecting little ferry ordered not to sail.

Despite all this, Breivik was instantly ferried across, no questions asked, heavily armed and politely assisted with the carrying of ammunition boxes both onto and off the the boat.

Upon landing, he almost immediatly shot and killed the police officer, who despite apparent doubts had not taken up any countermeasures. And then of course killed 68 more, plus wounded about twice that number.

With a phone call and a modicum of due diligence, everyone would have been safe.