pff that's lame
just don't ruin their belongings
There's plenty of things that aren't excluded by those rules. You just have to be creative and think of more than "lol let's hurt them and break their stuff!" That's not a prank, it's just being a richard
I think op mentioned one of them having a laptop, so personally, I think I'd write a program (as a window service, so they wouldn't see it in task manager) that automatically starts, and periodically maxes the volume and plays embarrassing sounds.
Of course you'd have to get access to their laptop. Probably disguise it as something and leave it on a disc somewhere they'd find
That's covers the "don't hurt them", makes far less disruption then a horrible smell all over the school, and be harder to track back to you than the other suggestions
Poll