Trip on a piece of grass.
From Create Your Own Story
You are sprinting really fast and you see a lump on the ground. You slow down to try and miss the lump on the ground. You slow down too much and you see what it is. It is only a piece of grass, you still are running but you've slowed down just a little bit to much. Your toe gets caught under the piece of grass and you fall really hard onto your tummy.
