grublox/v1.1/avatar-fetch.php

<?php
if(isset($_GET['userId'])) {
    $id = $_GET['userId'];
    // we do not care about the placeid literally
    if($id == '0')  {
        die('http://roblox.com/asset/?id=76157786;http://roblox.com/asset/?id=129459077'); // default guest avatar
    }
}
?>