It was the funeral of the local traffic warden.
Just as the vicar was about to throw soil in with the "Dust to dust" routine he heard a loud banging from the coffin and a voice wailed in terror, "Help, help, I'm not dead, there's been a terrible mistake."
The vicar paused, wondered what he could possibly do then said, with a wry smile, "Sorry, but the paper work has already been done."