It not just meant to expando script you can apply any of the HTML Script ot your WordPress Blog, just follow the below instruction:
<script type=”text/javascript” src=”http://coolabhay.com/wp-content/uploads/2009/04/expando.js”>
</script>
>> This code is a reference to expando.js, download it or let it be like this.
1. Copy the code below..
2. Open theme editor under design tab of your main screen of Dashboard.

3. Find the head portion of the theme, particularly you will find it in header.php

4. Paste the code for the head portion of Expando Script.
5. Pasting the code before </head> is preffered.
6. Now what do you want, it is done.
Add
class="expando cat"
in image code to add effect.
Eg.
<img class="expando cat" border="0" src="put the image address here" width="200" height="88">