Have left over bath water you don't want to wash down the drain after only one usage? A kitty bath is a great second use for it!

(Click this photo to see my kitty bath series, featuring The Smooch!)
Docile cats are probably best for this. If they're overweight, even better, as they seem to procure fewer physical objections, and only more miserable kitty moans.
When all is said and done, your cat will thank you, or at the very least feel softer.