Well, I believe that military procedure states "to watch where the fragmentation device stops rolling, and then to lay down on your stomach, facing away from it".
This is because:
A) Shrapnel from the blast would not likely fly close to the ground, as it would be directed upwards from the explosive blast.
B) If said shrapnel did hit you, it would have to travel through your legs before it could reach your vital organs, thus slowing it down, and most likely stopping it.
...but I'm not in the military, so I'd most likely stare at it in pure shock. *boom*