fosk

<div style="visibility: hidden;">
    Please don't insert any text in the input below. If you do this your comment will be refused!<br />
    <input type="text" name="hiddenForm" value="" style="width: 1px; height: 1px; font-size: 1px;" />
</div>

<?php
if (!isset($_POST['hiddenForm']) || (!empty($_POST['hiddenForm']))){
    echo '<html><body><p>Spam detected</p></body></html>';
    exit();
}
?>