Over in the United Kingdom, there’s a certain dessert known as a “teacake” — or, as a British friend kindly informed me, it’s more accurately known as a “Tunnock” in Scotland. Basically, the food in question for this particular story are actually a cookie base topped with marshmallow, coated in chocolate, and wrapped in foil. Believe it or not, these marshmallowy treats ended up on the Royal Air Force’s no-fly list.

Let’s set the scene: Back in the late 1950s and early 1960s, the Cold War was in full force and it was believed that RAF bombers going through five-hour flights needed plenty of snacks to keep their heads in the game.

These airforce members were generally flying a Vickers Valiant, a British high-altitude jet bomber that was designed to carry nuclear weapons. In peacetime, recounts that the Valiants were pressurized to remain at the equivalent of about 9,000 feet, even when the planes were high in the air; new recruits, though, would undergo full depressurization at around 40,000 feet, just so they’d know what that felt like.

“There was usually a loud bang and the cabin instantly filled with an icy-cold white fog followed by the release of unpleasant bodily odors as intestinal gas expanded rapidly,” Cunnane explained in a blog post.

Well, since these new trainees were often busy snacking, it was inevitable that someone would bring one of their beloved foil-wrapped teacakes.

Here’s a little more from :

Shortly after the foil-wrapped treats appeared in RAF ration packs, pilots began to notice that as altitude increased, the teacakes expanded. At 15,000 feet, the marshmallow interior cracked the chocolate shell. Air crews removed the teacakes from their silver foil packaging and perched them around the cabin for observation. The aerated marshmallow continued to swell as pressure changed, and the sweets became too big to eat in one bite. Many noted that, despite the extreme physical effects, the expansion didn’t compromise the taste.

Pretty cool, right? Well, it got a little more concerning:

But the expanding teacakes’ fame was short-lived. After a period of marshmallow fever aboard the V-Bombers departing from Gaydon air base, an explosion put a stop to the fun. During the summer of 1965, a captain and student pilot forgot they had placed unwrapped teacakes above their instrument panels. When the captain pulled an emergency depressurizing switch during a training mission, the treats erupted. Shards of chocolate and marshmallow hit the windshield, flight controls, and the mens’ uniforms.

Or, here’s what Tony Cunnane writes:

When the captain deliberately operated the emergency depressurise switch, both he and the student pilot had completely forgotten about their marshmallows, minus their protective foil, sitting on the ledge above the instrument panels. They, the chocolate teacakes, disintegrated explosively and bits of chocolate and shredded marshmallow splattered all over the windscreens, the flight instruments and the pilots’ flying suits. This rather distracted the pilots from the immediate emergency actions they were supposed to take for aircraft and aircrew safety.

As you can imagine, getting distracted from the whole “practicing our emergency routine in the event of sudden depressurization” thing wasn’t looked upon too highly. That chocolatey explosion resulted in a no-fly order placed on those poor little treats, despite all the rage.