It happened last Saturday night at Bedworth festival:
The "Voices" concert was 10 minutes from finishing at the Arts Centre Theatre, while an organised singaround was taking place at the theatre bar, separated from the main venue by two pairs of double doors. To close the singaround, the guy that "ran" the singaround said (jokingly): "Right, let's finish with a chorus number to show the Voices next door what we can do".
So far so good. But the next person that sang launched then into Dave Webber's "Parting Song". And we ALL knew (including the singer) that Dave and Anni were headlining the Voices concert next door. And that Dave would probably want to finish with his "Parting Song".
So we "showed" them next door - what prats we were...