Good King Wenceslas
I recall one Christmas Eve, my mother, a lay magistrate, being called in for an emergency court case. An American citizen due to fly back to North America on Boxing Day, had been accused of threatening behaviour towards a police officer.
Basically he and his friends had been on the piss the night before, had a good time and one had been arrested for something or other. Anyway, the American tried to get him bail from the Police Station, as this is possible in the USA. This was explained by him in court, and there had been a 'misunderstanding' by the Police Officer in question.
Anyway, when describing why the person had been arrested in the first place, a rather dour police sergeant explained that the group had been singing rather loudly, and although the tune had been 'Good King Wenceslas' "they were not the original lyrics".
One can only hope that the lyrics actually used were recorded in the court transcript.