"Stool" is probably a more descriptive term than what it is really called, which is probably along the lines of "EMERGENCY LANDING GIRDLE, HARRIER, REINFORCED, MIL-STD 9503" and conveniently priced in the upper five figures.

If that were the case, it wouldn't be a stool, it would be an ELGHR. It looks pretty uncomfortable, too, especially for upwards of $10k.

Clearly its a Support Tool On Oversized Legs :-)

Nah, the military doesn't have a sense of humor.

The purpose-built tool for main (rear) gear failure must be an interesting-looking piece of work.

I don't understand the distinction you are trying to make. Even if it's purpose built, it still fits the definition of a stool.

All the stools I've ever sat on would be about as tall as one of the wheels and would have been crushed to splinters...

A stool is something I sit on, not something an aircraft lands on.

Schrodinger's stool? the stool is not until it's sat on?

That was my first thought when I read the title. What, a stool, like one I would sit on? A barstool or something? What stool wouldn't be completely destroyed by any aircraft landing on it?