Thanks to dog.ceo and its API, you can display a random beautiful dog in a website. Just add the code below in your PHP:

<img style="width: 100%;" src="<?php
$my_json = "https://dog.ceo/api/breeds/image/random" ;
$my_content = file_get_contents($my_json);
$my_content_dec = json_decode($my_content);
$url_img = $my_content_dec->message ;
print $url_img;
?>" alt="Oh my dog!" title="Oh my dog!">

 To restrict the joke to your users (more polite), just enclose the code with this kind of PHP condition.

<?php if ($user->id != 0): ?>
   ...
<?php endif; ?>

 In Joomla a perfect spot to put it: templates/your_template/index.php, into the <div id="aside" class="span3">.

Please let me know if you find other APIs like it!