Don't put fake warnings on your prints.
Not long ago I was scrolling social media and found that someone had posted a fairly real looking 3D printed canister of Cobalt-60 (a highly radioactive substance) labeled as:
"DROP AND RUN"
It was fake, but a layman not familiar with either 3D printing or such canisters might be scared. In fact, causing fear was the goal of the post, per the original text. The Poster thought it would be funny.
I cannot fathom why people put files like these out there.
The issue, which seemed to escape this person, is that causing terror is not funny. Lesser acts have resulted in calls to the police, bomb disposal, and radiological containment/clean up, and cause huge disruptions costing millions of dollars. If that distraction also cost someone else's life, the poster would have become a party to manslaughter. Talk about a, "See you in court." moment.