Yeah this is big exploit,I remember when I was doing the same crazy things-)
Try to build another Tower of Babel-)
Haha, but is it an exploit per se? I'm not sure what it could be used for, aside from impossible towers!
The only thing we can do is sit really, really high up. We can't build it up and past a wall, and hop off; to sit on the bench, you have to be able to approach under and 'beside' it, as if it were on the ground. To do that, you'd have to be able to walk legitimately into the area you built into, anyway.
