My son was about 6 when I brought my Kimber home. I brought him in and showed him how to check to make sure it was clear. We discussed the 4 rules then I told him he could look at it/inspect it any time he wanted to; he just had to ask me. With the novelty and desire for the forbidden removed he has never tired to sneak behind me to play with it. The watermelon sounds like a good approach too. Wish I would have thought of it then.