Riddles Wisely Expounded (the one that goes):
There was a lady in the North Countree
Lay the bent to the bonnie Broom,
And she had lovely daughters three,
Fa la la la la la la la la.

can be magic if you get the audience to pick up your speed and intensity.
MacColl and Seeger made a great job of The Baron of Lys by dividing the audience into men and women
Women:
Come tell me you, come tell me true,
Come tell me how they ca' ye,
Your gentle blood lies 'tween my two sides,
And I dinna ken hoo they ca' ye

Men:
Some ca' me this, some ca, me that,
I'm easy hoo they ca' me
(last two lines carried by the singers because they vary as the baron tries to dodge giving his name to avoid his paternal responisbility)

Regarding "audiences joining in" - I've always been opposed to this happening on anything other than choruses, unless invited.
Confirmed by a giant pain-in-the-**** last weekend at our annual singing festival - who joined in on virtually every song, verse and chorus - quite audibly, and when she didn't know the words, she hummed the tune, also quite audibly - a singer of long enough experience to know better - or does that type of happen often in the UK?
Open season on such behaviour here next year
Jim Carroll