[Monkeyboy_McGee]

Well, first-glance suggests a cave entrance, but then you think "well that really doesn't look like a cave. I've seen caves, and this isn't one".
Then i thought it might be someone's inside, like the entrance to a stone woman's womb or something =x
Or just some pipe in the body. But then you think "well he obviously didn't try to draw that o_O" and so all i saw in the end was a load of grey shapes next to each other.

It was kewl to see what everyone saw, its amazing what you can get out of one picture with lots of different brains!