Dirty Playground Magento 2

Playground Dirty - test.php

//put under pub/test.php

<?php

require dirname(__FILE__) . '/../app/bootstrap.php';

$bootstrap = \Magento\Framework\App\Bootstrap::create(BP, $_SERVER);

/** @var \Magento\Framework\App\Http $app */
$app = $bootstrap->createApplication('TestApp');

$bootstrap->run($app);

TestApp.php

//Put under pub/TestApp.php

<?php
class TestApp extends \Magento\Framework\App\Http
    implements \Magento\Framework\AppInterface {
    public function launch()
    {
        //Using object Manager
        // $object =  $this->_objectManager->get('your classs');
        echo "Hello World! My Dirty Playground";
        return $this->_response;
    }
    public function catchException(
        \Magento\Framework\App\Bootstrap $bootstrap,
        \Exception $exception
    )
    {
        return false;
    }
}

Open http://<your_magento_host>/pub/test.php to see the result.