Mine

function bw($string){
// words to filter
$aBadWords=array("word1","word2");
//
    foreach ($aBadWords as $key => $word) {


        $aBadWords[$key] = "/({$word})/ie";

    }


    $return  = nl2br(preg_replace($aBadWords,"str_repeat('*', strlen('\\1'))",$string));


return $return; 


}