In any city, in any country, go to any apartment building. Make sure whereever you're going has exactly 7 floors or higher. Go to the 7th floor and approach the apartment at the end of the hallway. When you get there, knock on the door 7 times, no more, no less.
Now be prepared to wait a long time, for no one will respond for some time. You may wait from seconds to even weeks, but you must not leave the building. When you do hear a response, enter. There will be no pictures or furniture of any kind in the room that you are in, but do not avert your attention anywhere but at the center of the room where The Holder of Insanity is standing.
He will look at you for a while and finally ask, "Do you know of true insanity?" If you do not, then you must exit the building immediately and forget the experience ever happened. But, if you do, then answer "yes" and he will leave the room and you alone. You must not leave no matter how long you are there until you start slowly going insane again, losing your grip on reality.
Frightening images and sounds will enter your mind and will force you to your knees, but you must not leave that room. Nothing will matter to you anymore, not even your family.
Now, what happens next can't be explained or put into mere words, because you can not describe true insanity. It is not known exactly how long the experience will last, but it is most important that you do not leave the room, for if you do, it will never end.
However, if you survive and are still in the room, The Holder will return. In his hand will be a light bulb. This light bulb is object 2007 of 2538.
Credited to TheGrimman