If zombies was to come up to you and you shoot them, they will keep coming until they have had their brain destroyed. Life as we know it, zombies are getting more and more possible to become real. If people keep doing what they are doing this very day, we are all doomed.
The reason for why people could possibly became zombies and the world being populated with them is simply the fact of our life style. Right now we could all be just mindless zombies, wanting nothing more then to go one the Internet or couch around on the lounge. If we get into a life style that isn't like that, then we are bound to not live like zombies.People these days are becoming zombies, because they want more blood and flesh and perhaps in some case brains. Everyone, get out your shotguns!
I wouldnt take this as a joke because It could happen real soon!