The title of the thread contains both club and session, the two are not synonymous.

As the OP, I must say that in this context Folk Club and Session are pretty much synonymous. Our Folk Club is a music & song Session; there is no emcee, no floor spots, no formality, no order, no performances as such where anyone is free to sing when they want, or as much or as little as they want. It is convivial anarchy. It is a Folk Club where people meet to play (mostly) traditional tunes & sing traditional songs, where joining in actively & heartily encouraged.

The point is that even in this context, why is it that people feel the need to join in when they obviously don't have the first clue what the music is about? And why, having placed me in the awkward situation of having to advise them mid-song that their contribition is not required, do they take offense and start demanding what The Rules of contruibition are? Surely the rules of contribution are obvious: only join in if you know what you're doing. If you don't, shut the feck up and LISTEN. I do a lot of LISTENING at our Folk Club, I am like a pig in shit doing so, enjoying the seasoned experise and virtuosity of muscians whose boots I am not fit to lick*. But even here, certain indivuals feel the need to play along when they haven't got the first clue.

Whilst I am no fan of people who persist in singing along with my shit (or anyone's shit for that matter) to show their appreciation or that they know the song too, I have no problems with those who 'air sing'. Ever seen that? I know two people - both of them great performers in their own right, both of them very dear to me as people too - who sing along with every word in studied concentration, but (get this) they don't utter a sound.

* Not just seasoned virtuousi I might add. I love listening to other singers in Folk Clubs, it is one of life's true joys; even the most nervous & inexperienced of singers can touch my heart, and very often do.