It was the OTO Modello 35 Italian hand grenade along with similar models from Breda and SRCM. The nickname came from the widespread use in North Africa of the Breda and SRCM models as a anti-personnel mines. This resulted from their rather spottly working fuze mechanism that required the grenade to hit something solid and upset a ball and pin mechanism. So, the Germans and Italians found that you could pull the fuze tab out and gently place it on the ground. If disturbed by walking on it or kicking it, it usually went off.