Soldiers play Hot Potato with a life grenade. This can easily be faked. Imagine, you’re tossing around a bean bag, you throw it in a hole then a safe “poof” set off by a person off camera.
Still, what’s the point? Is it to test their calm? What if one soldier drops it, which is why they’re practicing in the first place? An explosion at their feet? What if it goes off early? Grenades don’t have electronic timers. When are they going to have a grenade in the palm of their hand that’s tossed to them? Is it like a football option play or “flea flicker”?