a tube train chuntering along in the outer suburbs.
A commuter, minding his own business (played by your humble servant)
An idiot (played by an idiot)
So there I am reading the paper and I become aware that the idiot sitting three seats along is shouting numbers into the air. I glance around and note that he is using a mobile. He repeats the numbers and I realise this is his credit card. He goes on to announce his security code, expiry date, and his name and address.
So now I am able, should I wish, to get on my mobile and (once he leaves the carriage) put a really big crimp in his day.
Lucky for him I am basically honest. But I can't speak for the other passengers. I wonder if he has a nasty surprise in store...