The Desert Goat Hole
So there's these three guys walking through the Arabian desert, and they've completely run out of water.
They manage to keep walking until they spot a well out in the distance.
They excitedly hurry to the well only to find out that it's too deep, and they can't even see the water at the bottom, so they devise a plan.
The first guy drops a pebble into the well, and they listen for a splash, but nothing happens.
So the second guy drops a rock in, and they listen...but …