A man stumbles into a deep well and plummets a hundred feet before grasping a spindly root, stopping his fall. His grip grows weaker and weaker, and in his desperation he cries out, "Is there anybody up there?"
He looks up, and all he can see is a circle of sky. Suddenly, the clouds part and a beam of bright light shines down on him. A deep voice thunders, "I, the Lord, am here. Let go of the root, and I will save you."
The man thinks for a moment and then yells, "Is there anybody else up there?"
This joke appears in the chapter on "Reason vs. Revelation" in Plato and a Platypus Walk Into a Bar: Understanding Philosophy Through Jokes by Tom Cathcart and Dan Klein. Both the book and the authors have been profiled here; a quick excerpt:
On [a] vacation in 2004, in Gloucester, they brainstormed about Klein's idea of a book of philosophy and jokes. Cathcart had said there can't be more than four jokes with philosophical implications, but Klein was sure there are hundreds. At the end of the trip, they agreed to give the book a try and soon got down to serious -- but not too serious -- research and development. [...]
Klein dug up most of the jokes, while Cathcart explained the philosophy. Yet they collaborated closely on both parts.
Klein: "We figured out that jokes and philosophy have a lot in common. Every joke has that 'aha!' moment."
Cathcart: "One reason you laugh at a joke is that you are so delighted with yourself that after that split second, you 'got it.' There is that experience with philosophy -- some ideas are a little offbeat. You have that moment when you don't get it, and then you say, 'Oh, right!' "