@mangeurdenuage
Real story.
I came to school with retractable blunt knife toy.

After one hour I get called to the office.
Teacher starts explaining to me how dangerous weapons do not belong to chool.

I am bored, so I start retracting the knife against my palm...

Teacher looks at me: "That's the knife I was told about?"

It was obvious how hard it was not to facepalm. He released me immediately.