At the beach, there's this bluff. It's like a hill, but at an 80 degree angle. It's over 100 yards from top to bottom.
I decide to run up the hill.
Near the top, I realize I won't make it. So I make my way down. I lose control and start running, reaching a top speed of at least 15 MPH (or so my friends said). All I remember is hitting my face against a tree branch and landing face-first in a bush.
(For those wondering, I did it before and made it, so I thought I could do it again. It turns out I was thinking of a different hill, which was very close to the hill I hurt myself on.)