“This is the end, my only friend, the end”
~ Jim Morrison on The End
End is one of the most dangerous keys of a computer. If you press it you will be transported to the end of the world. It is, in fact, a form of time travel. It often includes a protection from accidental pressing: once it is pressed, you have 5 seconds to press the ESC_key and escape the situation, if it hasn't already legged it.
On a Mac, it makes your computer feel the need to put your boots on, kill your father and make sweet, sweet love to your grieving mother.
Just for your information, when you press the key with ALT key, you can select alternate routes to the end of the world.