Guns. As even a trigger-happy, AK-47-toting, hollow-pointed bullet fan Rambo will agree: in the wrong hands they can do rather a lot of bad.
Ask the cops in South Auckland who discovered a worrying cache of high-powered firearms in a suspected drug dealer's ceiling. Ask the four cops shot in the Bay of Plenty and their colleagues who calmly resolved the Kawerau siege.
And ask Jamie Gilt, the Florida mum who this week was shot in the back by her 4-year-old son with a .45 caliber handgun.
I don't want to be too nasty about that last incident given Gilt was fairly seriously injured when her son picked up the pistol from the floor of the family pick-up truck and somehow hit the trigger.
Except there is a certain irony in a gun advocate being shot by her preschool son, a certain irony in Gilt's recent social media posts where she had boasted of her son's shooting ability.