As a Customer Service Officer at a well-known London terminus, I see and hear stupid or amusing things just about every day.
But the best one I've seen was as a passenger.
I was waiting on the Circle Line platforms at Paddington, when a Hammersmith train came in, so I stepped back to let those passengers on. A guy came charging down the stairs, across the platform and jumped on just as the doors were closing.
Unfortunately, the doors closed and trapped his shoe. Not realising the doors would re-open, he tried to pull his foot free but only succeeded in pulling his foot out of his shoe. At that point, the doors opened, releasing his now empty shoe, which then fell out of the train, bounced on the platform and fell under the train

The doors closed, the train pulled away, the guy is stuck on the train with one shoe...