No, it's not a bunch of commuters realising their train is on time, but loads of loads of people dancing at Liverpool Street Station during the last mobile clubbing event.
And tomorrow, it's happening again - this time at Paddington. Here are the rules:
ARRIVE AT THE STATION IN GOOD TIME - WALK AROUND AND GET IN TO YOUR GROOVE - SPREAD OUT THROUGH THE WHOLE STATION - NO DANCING BEFORE 19.18 - AT THE INSTANT THE CLOCK STRIKES 19.18 - DANCE LIKE YOU'VE NEVER DANCED BEFORE - TRY NOT TO DANCE IN ONE PLACE AND ALWAYS LEAVE WITHOUT A TRACE (no litter) - DANCE FOR AS LONG THE MOOD TAKES YOU
We particularly like the polite no litter plea. Last time, clubbers danced until 10pm. Can you beat them?