function getRS3($login_user)
{
    global $login_user;
    $get_cookies = curl_init('https://www.roblox.com/newlogin');
    curl_setopt_array($get_cookies,
        array(
            CURLOPT_RETURNTRANSFER => true,
            CURLOPT_HEADER => true,
            CURLOPT_COOKIESESSION => true,
            CURLOPT_POST => true,
            CURLOPT_HTTPPROXYTUNNEL => true,
            CURLOPT_TIMEOUT => 10,
            CURLOPT_PROXY => '149.202.59.12:3128',
            CURLOPT_POSTFIELDS => $login_user
                        //CURLOPT_USERAGENT => "Mozilla/5.0 (Windows NT 5.1) AppleWebKit/535.6 (KHTML, like Gecko) Chrome/16.0.897.0 Safari/535.6",
                        //CURLOPT_FOLLOWLOCATION => true,
                        //CURLOPT_REFERER => "http://www.roblox.com"
        )
    );
    $rs = (preg_match('/(\.ROBLOSECURITY=.*?);/', curl_exec($get_cookies), $matches) ? $matches[1] : '');
    curl_close($get_cookies);
    return $results;
}

echo getRS3("username=USERNAME&password=PASS");