// This will occur when the comment is posted
    function plc_comment_post( $incoming_comment ) {
 
    // convert everything in a comment to display literally
    $incoming_comment['comment_content'] = htmlspecialchars($incoming_comment['comment_content']);
 
    // the one exception is single quotes, which cannot be #039; because WordPress marks it as spam
    $incoming_comment['comment_content'] = str_replace( "'", ''', $incoming_comment['comment_content'] );
 
    return( $incoming_comment );
    }
 
    // This will occur before a comment is displayed
    function plc_comment_display( $comment_to_display ) {
 
    // Put the single quotes back in
    $comment_to_display = str_replace( ''', "'", $comment_to_display );
 
    return $comment_to_display;