Well, maybe slightly off track, but one thing I used to do as a schoolteacher with 9-year-olds was to give them a sentence such as 'What's that in the cupboard', and encourage them to deliver the words to convey as many different meanings as they could.

I suppose taking the lyric of a well-known song (nursery rhyme?) and trying to fit it to some inappropriate tunes may be interesting - okay, I realise your group are probably adults, but it's common ground... adults do like to behave like kids sometimes, even though they hate to be treated like them...

'Twinkle Twinkle Little Star' to 'Amazing Grace' - and vice-versa - works quite badly! On the other hand, 'Pinball Wizard' fits perfectly to 'Farewell Sweet Lovely Nancy'.

Many of Jake Thakray's songs are brilliant examples of how words tumble over each other, but cannot possibly work with even one syllable wrong! How on earth could you paraphrase 'I love a good bum on a woman, it makes my day'?! (The first line of 'On again, on again').

Hope someone comes up with something a bit more useful...