The Scary Door
You are entering the vicinity of an area adjacent to a location. The kind of place where there might be a monster, or some kind of weird mirror. These are just examples; it could also be something much better. Prepare to enter The Scary Door.
That's from Futurama, in case anyone was wondering. It's a parody of The Twilight Zone.
Seriously, though, we have a scary door in our house. It's the coat closet by the front door. It frequently opens on its own. One morning I was sitting alone in silence, eating breakfast before work, and I heard this creaking sound that nearly necessitated a change of pants. And it's even worse if you happen to be in the room when it happens, because you can see a sliver of darkness when it opens. Jibblie jibblie jibblie.