These days, lots of public libraries have a "library of things" collection where you can check out kitchen appliances or yard tools or toys, and, as a children's library assistant, the most popular library of things item that I handle regularly is a plastic scepter thingy called like "unicorn princess magic wand". And whenever I check it out I make a big show of looking at the little kid and being like "do you solemnly swear to use your unicorn princess magic powers only for good and never for evil?"
And pretty much without fail, the little kid will get the world's most mischievous grin and go "I'm gonna use it for EVIL!!!"
