se_random_post.php

<?php

add_action('init', function() {
	
	// rewriting site.ext/index.php?se_random_post=1 to site.ext/random/
	add_rewrite_rule(
    	'random/?$',
    	'index.php?se_random_post=1',
    	'top'
    );

});

add_filter('query_vars', function($vars) {
	
	// saving the query variable for the rewrite rule
    $vars[] = "se_random_post";
	return $vars;

});