On a more serious note, the Yellowstone explosion isn't what will kill most of us. Even if the explosion itself is a complete surprise (unlikely), we're well outside the worst of the shockwave and would have plenty of time to head south or west or wherever we need to get out from under the nastiest of the fallout.
The years after would be far worse. The environmental effects of a supervolcano like Yellowstone popping off would cause something very similar to a nuclear winter. Food shortages and the resulting crime would be devastating.