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A few things about that. First, there's actually a poison that makes that happen, just not the same, its like your dead, everyone sees you dead, but then randomly you jolt or move for a second. Second, there are ways to stimulate brain waves again that cause temporary zombification, but it requires a lot of power and goes back away. Third, there was once a scientist who was totally insane and brought a decapitated dogs head back to life, it just acted normal, even ate a treat.