I took a drawing class in college. On the first day, we were encouraged to rearrange the classroom into a non-conventional setup, so most of the students (and the professor) ended up cross-legged on top of their desks. The professor still sat in front of the classroom and gave us an hour-long condescending speech on his policies and expectations.
Sorry, but that's the same kind of "thinking outside the box" as getting conventionally married, but then getting matching tattoos instead of rings. Or getting conventionally married, but then getting plastic surgery to look like one another, instead of rings.
The thing about desks is that they're only good for their intended purpose when you're working on something that needs to be on a flat surface directly in front of you. On the first day of class, of course that's irrelevant. But as time goes on, you might actually want to use the desk when convenient. Like, uh, when you're drawing and need a flat surface that isn't the floor.
If you go and sit on top of the desk, it should be because you understand that it's not particularly ridiculous, that it's not a big deal, and that there's no reason not to. Never because you DO think it's ridiculous, and you think it's some kind of brilliant way to push "boundaries" that a person only observes in the first place if they're hopelessly oversocialized.