In the lore of Karl Barth, are two nursery rhymes that Barth used his great wit to respond to questions.
Jesus Loves Me
According to the best accounts of the incident I have heard (many have taken on weird additions), Karl Barth was at Rockefeller Chapel (really a Gothic cathedral!) on the campus of the University of Chicago during his lecture tour of the U.S. in 1962. After his lecture, during the Q & A time, a student asked Barth if he could summarize his whole life’s work in theology in a sentence. Barth allegedly said something like “Yes, I can. In the words of a song I learned at my mother’s knee: ‘Jesus loves me, this I know, for the Bible tells me so.” That is the simple, unadorned story. Many tellers have adorned it with additions of their own (in sermons, etc.).
(source: Roger E. Olson, "Did Karl Barth Really Say “Jesus Loves Me, This I Know….?”")
Twinkle, Twinkle, Little Star
After the service in a parish church where Barth had been preaching one Sunday, he was met at the door by a man who greeted him with these words: "Professor Barth, thank you for your sermon. I'm an astronomer, you know, and as far as I am concerned, the whole of Christianity can be summed up by saying, 'Do unto others as you would have others do unto you.'" Barth replied: "Well, I am just a humble theologian, and as far as I am concerned, the whole of astronomy can be summed up by saying, 'Twinkle, twinkle, little star, how I wonder what you are.'"
(source: John D. Godsey, ed. George Hunsinger, "For the Sake of the World: Karl Barth and the Future of Ecclesial Theology")
Related: Jesus Loves Me, Karl Barth, Nursery Songs, Twinkle Twinkle Little Star