Charlie felt an opportunity was missed here. He was surprised the man had followed up on the question at all.
For his own response, Charlie momentarily halted his playing. A hand slipped into his pocket, and he produced a green guitar pick. Up until now, he'd been playing with his bare fingers. "This," he said, as he resumed his song. "Playing with a pick."
On another day, Charlie might have also thrown in, Now don't you feel stupid. Today, however, he thought better of it.