During WWII, all sides tried to come up with new military products for use in the war. Some were real breakthroughs and others, well not so much. And that brings us to the T13 "Beano" Impact grenade. Standard fragmentation grenades are used by pulling out the pin which holds the "spoon" or "paddle" on. When the pin is pulled, spring pressure throws the paddle off the grenade and ignites a fuse that burns for approximately 3 to 5 seconds and then detonates the primary explosive. The Beano worked differently. Instead of a timed burning fuse, it used a pressure trigger and an in-flight arming mechanism. To throw the grenade, the user would grip it like a baseball, that is with the first and middle finger together over the top of the grenade and its knurled "butterfly cap". Then the pin was pulled and the grenade thrown. The butterfly cap would come off when the grenade was thrown and then a nylon cord attached to it would play out until it pulled a second arming pin from the interior of the grenade. This armed the grenade to explode when it impacted a hard surface.
Obviously, this raises some important questions. What if you threw the grenade and it landed in soft dirt or mud or water? You have a highly dangerous piece of UXO is what. How much pressure is needed to pull the secondary arming pin? Would it fail to work or be pulled accidentally? How sensitive is the impact fuse? Could you tangle the cord and butterfly cap in gear or barbed wire and cause the grenade (now armed) to come back at you like a tetherball?
The T13 grenade was developed by the OSS, the forerunner of the CIA and manufactured by the Eastman Kodak company. The idea behind its shape was that American soldiers were almost all familiar with throwing baseballs and that they would be able to throw a baseball-shaped grenade further, more accurately and with greater ease than the oblong shape of earlier grenades like the Mk2 "pineapple" grenade or the Mills bomb. Despite accidents and deaths during the testing process, the T13 was approved for field use and some 10,000 were sent to the field for use during the Normandy invasion. It was apparently withdrawn due to a high incidence of accidents and injuries from misuse or poor design. Most existing examples were destroyed and the plans classified. There was a similar design from Italy called the SRCM 35/38 or the "Little Red Devil". It was used during the same time period and there are many documented cases of the grenades being found in an armed, but undetonated state, sometimes killing those who further disturbed them.