Code
<script type="text/javascript">
var messages = document.getElementsByTagName('td'), j = messages.length;
while (j--) if (messages[j].className == 'posttdMessage') {
messages[j].innerHTML = messages[j].innerHTML.replace(/(ваши|матные|слова)/g, '<span title="$1" style="color:red;">***</span>')
}
</script>
