This tragic story is one of most to the point demonstrations I can think of when you fail to follow every law of gun safety:
1) Treat every firearm as if it is loaded.
2) Never point weapon at anything you are unwilling to destroy.
3) Be aware of your background.
4) Keep the finger off the trigger until you are ready to fire.
If only he had followed Law 1. Or if not, then Law 2.
Teen Did Not Think Gun Would Go Off