I had a small collection of cool '90s pencils from childhood boxed away in the attic at my grandma's house. One I really liked that changed colors with the temperature. My little nephew and his friends went through my stuff and raided them. When I discovered it, it was too late to say anything to him, my niece or any of their friends about it. I just got pissed and threw the rest away. I just let them think they got away with it.
Which upon reflection makes me wonder how much shit my parents probably knew me and my brothers were doing but stayed quiet and let us think we were getting away with, until we really fucked up.