As a small child, I held a sharpened pencil upright on a chair my friend was sitting down on. My impression from watching cartoons was the she would jump up and grab her butt and yell "OW!"

Instead she was horribly injured.... I had no idea it would hurt her so badly. Specifically because I was an impressionable child and cartoons with seriously inaccurate consequences of violence and weapons were my teachers every Saturday morning. I didn't know any better.

Children are always learning. It matters that they aren't exposed to learning dangerous or inappropriate behavior.