I've been told that a modern frag grenade explodes in a cone, so if you're laying on the ground next to one, no shrapnel would hit you.

I also have a friend whom was hit by a grenade while serving in Iraq. I asked him what it felt like after he was hit, and he described as feeling hot and painful, and his muscles around the entry point grew stiff. Luckily, there was no long-term damage.

Funny thing is...his twin brother, whom hadn't incurred any injuries, became an Army recruiter, while he got shipped back to Iraq.