A mate of mine nicked the life jacket on a BA flight once, as we returned from rugby tour. He may have got away with it, except he put it on as we got off the plane at Gatwick. He compounded the error by doing his trademark collapse on the floor just as he was walking out of the door, reviving himself to look up the FA's skirt.
He did not look quite so perky standing in the dock of Crawley magistrates court a month later, charged with 'endangering the safety of an aircraft'. A hefty fine, record and stern ticking off were the outcome.