Castle View School in Canvey Island, Essex, England, briefly banned triangular flapjacks (not pancakes; the English call granola-bar-like food "flapjacks") after a student sustained an injury when another student threw a cornersome flapjack at him. The school authorities required that all flapjacks must be served in rectangular portions, to increase the safety of food-fights.
The ban did not stand very long. Public mockery seems to have killed it.
According to one report, in 2011 British MP and Education Secretary Michael Gove was prevented from taking flapjacks into a cabinet meeting, after officials cited similar safety concerns. That is the only report of that alleged incident, however—although Gove was (and is) the Education Secretary, there does not appear to be any other evidence that he was ever frisked for flapjacks or that even the British government has actually classified them as a security risk.
I write books. My latest is a YA science fiction novel called Homeland (it's the sequel to Little Brother). More books: Rapture of the Nerds (a novel, with Charlie Stross); With a Little Help (short stories); and The Great Big Beautiful Tomorrow (novella and nonfic). I speak all over the place and I tweet and tumble, too.