Happened to me some years back - I'm retired now. Denver - London, the CSD came up and told me a passenger had moved from Traveller to Club, wrapped himself completely in a blanket, and would not respond when they addressed him. I went back and spake unto him at rather higher volume, inviting him to return to the seat for which he had paid. He said he needed a good night's sleep, and would pay for the upgrade. I said ''No problem'', wished him ''Goodnight'', and sent an ACARS message to a very useful department called Revenue Protection asking them to meet the flight.
You've probably guessed what happened next - when he met up with the RP people, he refused to pay -''What are you going to do - put me in gaol?'' The accompanying Security Officer clicked on his radio and replied,''No problem, Sir, the police will meet us at immigration.'' He paid.
Oh, and by the way, he'd left his wife down the back. I'll bet that was one happy holiday.
