Two guys were hiking in the mountains when they came across an old mine shaft going straight down into the ground.
"Wow," said the first guy. "I wonder how deep it is?"
"I dunno," said the second.
"Let's find out." With that, he dropped a rock down the hole.  They waitedand waited, but didn't hear it hit bottom.
"Hmm. Let's try a bigger rock," said the first guy, and tossed a watermelon-sized stone down the hole. They waited a couple of minutes, but didn't hear it hit either. So, they looked around for something bigger to throw down and came across an old railroad tie, which they lifted together and dumped down the hole. Then suddenly, as they waited to hear it hit, a goat streaked between the two of them and jumped straight down the mineshaft.
While they stood there scratching their heads in amazement, a third guy came up the path and asked them if they'd seen a goat.
"Yeah, just now," said one of the first two guys. "It just ran up and jumped down this hole."
"Oh, well then it couldn't have been my goat," said the third guy. "My goat was tied to an old railroad tie."