Here is a nightmare that is also real: The severed head of a cobra snake reportedly jumped out of the kitchen trash in a restaurant and killed the chef who was preparing its body as a meal. The chef, Peng Chen, had removed the head from the Indochinese spitting cobra a full 20 minutes before it bit him. One diner told the Daily Mirror, "We ... could hear screams coming from the kitchen."
The diner, Lin Sun, continued,
There were calls for a doctor in the restaurant but unfortunately by the time medical assistance arrived the man had already died. After we heard that we did not continue with our meal.
While this kind of accident is (obviously) rare, it's not impossible. The video below—which, warning, will haunt you forever—demonstrates how the severed head can act on its own.
[Image via YouTube]