Classic preacher joke, tweaked for the theologically literate
Barth, Bultmann, and Tillich went fishing one hot summer day. Being all three good German theologians, they brought plenty of beer, which they kept in a cooler on the shore, taking only the first six-pack into the boat with them.
After a while, when they had exhausted their beer, Barth said, "I'll go get us another six-pack." And he got out of the boat and walked across the top of the water to the shore, retrieved a cold six-pack, and walked back out across the top of the water and got back into the boat.
The sun shone down, and the fish avoided their lures. Soon, they were out of beer again. So Bultmann announced that he would go get the next cold six-pack. He got out of the boat, walked across the top of the water to the shore, retrieved another cold six-pack, and walked back out across the top of the water, settling down into the boat with a sigh.
After another hot interval, when the beer was once again wanting, Tillich announced that he would be glad to fetch them another six-pack. He got up and stepped out of the boat -- and immediately sank like a chunk of concrete. He was desperately splashing and struggling to stay afloat, when Bultmann turned to Barth and said, "You think we ought to tell that fool where the rocks are?"
And Barth replied, "What rocks?"