Some friends own a bit of land out in the country. With some wood left over from a project they built a stage and invited a few friends round for an "open mike" evening to celebrate a birthday. Guests welcome to bring a tent. Right at the end of the evening this guy turned up, got on the stage played his mandolin and then went. Nobody knows who he is or how he got to hear about the party. A wonderful end to the day.
Next morning it looked like Glastonbury, after the festival.
The rumour is that he once was in a well-known group.