But by definition it hasn't got a shared tune.

It might be fun trying to get a rendition at a Mudcat gathering. The point is, it isn't supposed to be people just murmuring away tunelessly, the way they sometimes do at funerals, it ought to be people with clear ideas of what the tune should be singing against other people who all have equally clear but contradictory ideas.

Very Mudcattish, though perhaps more noticeably so in some of the BS threads.