I accidentally had a pocket knife in my backpack after a camping trip when I was a kid 20 years or so ago. Being a good/naive kid, I told the teacher. Luckily the teacher was cool and said just leave it alone and we never had this conversation. That could have ended very differently with no tolerance policies starting around then.

In high school, many kids had rifles and shotguns in their cars to go hunting after school. Then we were old enough to keep our mouths shut haha.