Swear filter ideas

Hi all, Just wanting to pick your collective brains on this one: How do you go about implementing a swear / bad-word filter in PHP? Reasons for needing one aside, I'm just wondering if you favour a regexp, a substr_count, or what? Do you like to *** out the bad words, or just error back to the user? (I guess that is application specific). There are always ways to circumvent them, but I'm still curious to know how you prefer to handle it. Cheers, Rich -- Zend Certified Engineer http://www.corephp.co.uk "Never trust a computer you can't throw out of a window"