We used that Cockney ending to songs (you know, diddle iddle dah dah - BOM! BOM!) for the end of the Lord's Prayer. "Life everlasting - Amen!"
But our Brown Owl overheard us once and was Very Cross. No dancing round the toadstool for us that night.

I also remember several very irreverent Christmas Carols, which are no doubt on the music database here. One was very Norfolk as it had Anglia Square (a shopping centre in Norwich) in the verse:-

'We three kings of Anglia Square
Selling ladies' underwear.
They're fantastic, no elastic,
Seventy pence a pair...'