The Running of the Fall Leaves
Also referred to as the "Running of the Leaves" or ROTFL/ROTL, this annual "race" is actually just an pretext for sending as many ponies as possible running through the woods to shake the ground, causing the autumn leaves to fall off the trees. It is a long and arduous run, one that most foals (and many adult ponies) cannot complete. Naturally, certain very competitive ponies sometimes get carried away and put a lot more effort into trying to "win" than they do in making sure the leaves fall.
The Running of the Leaves traditionally comes two weeks after Nightmare Night (and one week after the end of Apple Bucking Season).