When you’re hammering a concrete piling into the ground and it slides out of view and disappears, just remember: it had to go somewhere. Thus, don’t grab a second one and start over until you find out what happened to the first, since for all you know it could have slammed into a subway train below you.
Instead, they slammed a second one in and…yeah, you can guess what happened. Amazingly, no one was hurt. Full story and pics at the link.