[Vicky.]

Erm. Sounds quite cruel, but if done regularly it should work. I dont think it will be a RSPCA thing either, as you wont actually be doing the cat harm? If its a really strong one though, do it from a distance incase you do actually hurt it..the shock of the water should be enough

We used to train our kittens not to climb the curtains/xmas tree/whatever by squirting them with a little spray bottle (one that you use for plants). Not quite what you are describing but it was extremely effective.