Two instances.

When Leonard Bernstein was to meet the Pope, one of his friends reminded him, “Remember, the ring, not the lips.”

When Louis Armstrong met the Pope, the Pope asked if he and his wife had children. Armstrong said, “No, pops, but we’re still wailin.’”

Terry Teachout, who has finished his Armstrong biography, assures me the latter story is both apocryphal, and true to character.