Grenades and other thrown explosives

When I was a kid the local army surplus store gave out xeroxed copies of "Murphy's Rules of War." Now I can't remember most of them, but one has always stuck with me, "A five second fuse lasts three seconds." While most modern grenades have five second fuses, but you can't count on it. Give it at least three seconds to blow. The thing is that if the grenade falls near your enemy, they can pick it up and throw it back, especially if it's sitting there for a while. Some people will pull the pin and let it "cook" for two seconds and then throw it. This can obviously be a problem for the above reason. So roll it or bounce it off a wall if possible so it is harder to catch and return. If you are making your own thrown explosives using a regular burning fuse, make sure to do a test burn so you know how much time you have.