The pin of a grenade keeps the handle in place. Once the handle is released it will spring off of the contact, starting the fuse - which are usually 3 or 7 second. You can remove the pin, and as long as the handle is held down, the grenade will not go off. Thus you can set a booby trap by placing the grenade so that something is holding down the handle, for instance a dead body, then remove the pin. When the body is moved off the grenade the handle comes off and the grenade is primed, so the soldier is killed by moving his comrade.
I also heard of an instance that relied on the fact certain electrical tapes are dissolved by petrol (gasoline). Tape handle, remove pin, drop in fuel tank. This gives you long enough to get away before the earth shattering kaboom.
The casing of a grenade is steel, designed to fragment when the charge goes off. There is no Hollywood explosion, picking men up and tossing them in the air. Anything strong enough to pierce the grenade is probably as powerful as the grenade.
Of course shoot a man who has just pulled the pin from a grenade, and he will almost certainly drop the grenade, taking pressure off the handle...
edited 23rd Mar '12 3:36:47 PM by LastHussar
Do the job in front of you.