Ninja rocks are broken shards of spark plugs. Since they can quickly and almost silently fracture the glass windows on most cars, ninja rocks are increasingly the tool of choice in "smash-and-grab" auto burglaries. They have no traditional association with the ninja or ninjutsu.
Ninja rocks are broken shards of spark plugs. Since they can quickly and almost silently fracture the glass windows on most cars, ninja rocks are increasingly the tool of choice in "smash-and-grab" auto burglaries. They have no traditional association with the ninja or ninjutsu.