bad-shortcode.php

<?php
/**
 * Plugin Name: Bad Shortcode
 * Description: Shortcode which outputs a script.
 * Version: 0.7
 * Plugin URI: https://gist.github.com/westonruter/6880918d45deb39c89e17f3b76583521
 * Author: Weston Ruter
 */

namespace Bad\Shortcode;

add_action(
	'wp_enqueue_scripts',
	function () {
		wp_register_script( 'bad-shortcode', home_url( '/bad-shortcode.js' ), [ 'jquery' ], '1', true );
	}
);

function shortcode() {
	wp_enqueue_script( 'bad-shortcode' );

	return '<script>document.write("Bad shortcode!!!");</script><noscript>Bad shortcode fallback!</noscript>';
}

\add_shortcode( 'bad', __NAMESPACE__ . '\shortcode' );