show random posts in this code

hello, i was wondering if any code gurus out there might be able to help: i’ve got client who’s using a child of the Neptune theme on her site and she wants to have the recent posts sidebar doodah to show a random selction of posts (obviously i’ll need to rename the doodah!) rather than the top 6 newest posts.

this is the code that fetches and outputs:

<ul>
<?php
	$my_query = new WP_Query('showposts=6');
	while ($my_query->have_posts()) : $my_query->the_post();$do_not_duplicate = $post->ID;
?>
<li>

	<?php if ( has_post_thumbnail() ) {?>
	<a href="<?php the_permalink() ?>" title="Permanent Link to <?php the_title(); ?>">
	<?php  the_post_thumbnail( 'neptune-minithumb', array('class' => 'custim3') );?></a>
	<?php } else { ?>

	<?php } ?>

</li>

<?php endwhile; ?>
</ul>

i know there’s a MySQL call for generating random results but my php coding chops aren’t up to the job i’m afraid. can anyone see where if at all i can make changes to this code to make it show the random selection?

the site in question is hierophant-nox.com if you want to take a look see the end results.

big thanks in advance guys. ??