Because the world is ending, and you're still reading this on your phone, because of course you are.
Buy as much toilet paper as possible. Trust us, you'll need it.
Look for a place with a good supply of snacks, preferably not a nuclear bunker.
Learn to make a mean Molotov cocktail, just in case.
Realize that, no matter what you do, you're probably going to die alone in a desolate wasteland.