There was a phrase that I used in my classroom when my students would ask me about doing questionable things, and my response was always, "Technically you can, but should you?"
The reason I used this instead of a simple yes or no answer is because it opened up conversation. Instead of blindly looking for permission, the conversation became more about cause and effect. Usually it navigated the "well you can't tell me what to do I'm going to do it anyway" instinct in kids when I'd say no, because all they were looking for is something to challenge them.
For example: "Can I jump off the slide?"
"Technically you can, but should you?"
If they answer no, I'd ask why. Usually they'd say because it's against the rules or I don't know.
If they say it's against the rules, I'd ask them why they think it's a rule. And if they'd say I don't know, I'd explain that the slide is five feet off of the ground, and jumping that high is a good way to hurt your knees or worse.
And then the most important part: if you did do it, how can you make it safer?
That's when the creativity juices started to flow. I'd get anything from pillows to beds to bouncy shoes to wings to someone catching them (which became a whole different conversation). And I told them since we didn't have those things here, it wasn't safe. And safety is everyone's number one job at school.
It stopped them from doing it behind my back. It got them to engage in critical thinking. And it helped them figure out how to do things without help.
However, there's always been an itching thought in the back of my head. Somewhere out there, did one of my past students drag their mattress out to the slide and jump off of it?