1) Little Jimmy is at a friend's house and comes across a loaded pistol left on a table by a negligent parent. Jimmy's parent's don't believe in owning a gun for protection and have always taught him that guns themselves were bad, only on the earth to kill, and can only be used for good when in the hands of the police or military. They also told him never, ever to touch a gun if he finds one. But little Jimmy is curious. The gun holds a certain mystique because they are forbidden to him. He's never seen one fired in real life, nor has he ever touched one. So he decides that while no one is looking he'll pick up the gun and check it out. He holds it, looks at the various parts, fiddles with the slide release, pretends to shoot it, makes "pew" sounds, looks down the barrel to see if he can see the shiny metal bullet inside, and then puts his finger on the trigger to see what it feels like. I'll stop there.
2) Little Tommy is at a friend's house and comes across a loaded pistol left on a table by a negligent parent. Tommy's parents have many guns, and have involved Tommy in shooting from a young age. They taught him how to safely handle weapons and also instilled in him a healthy dose a respect for guns as a tool that, when used wrong, can be deadly. They also taught him that they, as responsible parents, will never keep guns out of locked storage unless they are carrying or cleaning them. They also told him to always tell an adult ANYTIME there is a gun out that's not attached to someone's hip or being cleaned. The gun holds no mystique for Tommy, and he goes into the backyard where Mr. and Mrs. Potential Negligent-Homicide are arguing about the amount of chlorine to throw in the crappy above-ground pool and informs them that there is a gun out in the open and that they should put it up. They go in and put the gun up.