From ebay....
.....purchase a not inconsiderable quantity of pure metallic sodium. Sprinkle small cubes of this around your stove top, after making sure it is PERFECTLY DRY! Now spread rolled up balls of tissue and brand new tins of Lynx deoderant around the hob, over the top of the sodium.

When the cat urinates on them, they will smoke and catch fire, igniting the tissue, which in turn will cause the deo tins to explode in an enormous fireball, setting light to your kitchen.

The noise of the fire engine sirens, and the burly firemen chopping through your front door, should be enough to scare the cats away.
(NoveltyCondomHead Clanks Wams., Fri 1 May 2009, 15:41, Reply)