79th Street

I have an old shirt that says 'a rolling stone gathers no moss.' I was wearing it one day when a guy stopped me on the sidewalk. "A rolling stone what?" he asked. So I told him, "gathers no moss." "What?" he asked again. I looked at him for a second and started walking. He followed and kept repeating, "a rolling stone what?" until it took on its own rhythm in my head, and I was disappointed that I didn't have the right answer.