name1.php name2.php (gibt es nicht!)

<?php

error_reporting(E_ALL | E_STRICT);

if(!empty($_POST['action']) &&
   $_POST['action'] === 'jump' &&
   is_file($_POST['file'])) {

  $path = dirname($_SERVER['SCRIPT_NAME']);
  header("Location: http://{$_SERVER['HTTP_HOST']}$path/{$_POST['file']}");
  exit();

} else {

  echo <<< EOT
  <form action="" method="post">
    <select name="file">
      <option value="name1.php">name1.php</option>
      <option value="name2.php">name2.php (gibt es nicht!)</option>
    </select>
    <input type="submit" name="action" value="jump" />
  </form>
EOT;

}

highlight(basename(__FILE__,'.php').'.phps');