Shaking a load (e.g. boxes,
furniture) after tying it to a trailer, to assess if it is
sufficiently secured. To pass the Graham Hall Test: when you shake the load, it should also shake the trailer. If not, then you haven't secured your load properly, and
you should consider re-tying it.
That
Lawnmower definitely passes the Graham Hall Test; When you shake the mower, the trailer shakes too!
Let's do the Graham Hall Test, to make sure my fridge won't
fall off.