okay, what u do, is u ride with the seat dropped onto the ground, and then u grab the tire and hop up, dragging the seat underneath the wheel, and stand on the wheel, on the seat, but this will be harder on a bigger wheel.
I can’t do it, for more than a number of reasons, but there are a hell of a lot of u good tricksters out there, so see if u can do this.
and if this isn’t already a trick, i am calling it the “down UNder” or Frook for short.
Don’t ask why:D
People do that and hop over the seat (like sif to sib or the other way around) I have landed on the seat on accident before and it hurt alot.
Oh and you can only name a new trick if you are the first one to land it 
why frook?
anyhoo, I think it would be very bad for the unicycle seat, unless it was somehow either really strong, or really flat, either way it would be really uncomfortable.
It’s been thought of before, Pete66 came up with a very similar idea. Though nobody has done it yet.
If anyone tries make sure you have a CF seat…I can imagine a kh or similar snapping.