The thing about hymn singing is, if you can get the words to match the tune, you can sing any set of lyrics, or any poem, to any tune.

Here's a great non-hymn example: do you know the words to Robert Frost's poem Stopping by Woods on a Snowy Evening? Do you know the tune to Hernando's Hideaway? Then you have the perfect recipe for driving your choir director insane. Sing them together!

You may find this exercise somewhat frivolous, but it's an old tradition dating back hundreds of years. This is why, children, hymnals have so many indices. (That's plural for 'index'.) Look in the back of the hymnbook: there's the Alphabetical Index of Titles, there's the Topical Index (songs about God the Father, Jesus, the Holy Spirit, Mary if you're Catholic, patriotic holidays, Christmas, Easter, Pentecost, National Put Zucchini on Your Neighbour's Porch Day, etc, etc), the list of Authors, Composers, Sources, Translators and Arrangers, and a Metrical Index of Tunes. Ah, the Metrical Index. It is a wonder.

The Metrical Index contains mysteries. It lists things like 9.4.9.4 with Refrain, or 8.8.9.8. They're counting syllables. That's how you know that you can sing God Moves in a Mysterious Way to the tune Clonmel, which for some reason I can't find. But that's how I sing it.

You can sing Isaac Watts' When I Survey the Wondrous Cross to O Waly Waly. This is so popular these days, it's even in the hymnbook. Here's an organ version. You'll have to pardon the interruption partway through: the power went out in that part of town for a few seconds. It was a mix-up involving the electricians setting up the town festival outside on Main Street, and some antiquated wiring. Anyway, this accounts for the congregational giggling – they thought it was funny when I had to lean over and turn the organ back on. Congregations are easily amused, in my opinion.

It is possible to while away an hour or two of boredom on a rainy afternoon by counting syllables and mixing up songs, not just hymns. What mashups can you think up? The results can be hilarious, subversive, or inspiring. Try combining Amazing Grace and the theme from Gilligan's Island. Here's a bunch of 'Christian Mums' from Down Under with more naughty suggestions, especially involving the Aussie 'Match of the Day' theme. The mind boggles.