Until the day comes with the W3 grows a sense of humor, this will satisfy me, and any user with a Javascript enabled browser, for showing sarcasm in text. Just add the following sricpt into the head of your webpage and your good to go.

<script type="text/javascript">document.create.Element(sarcasm)</script>

I’m using it here with some CSS

sarcasm {
font-style: italic;
font-variant:small-caps;
font-weight: lighter;
}

And it should look like this:

You cubicle is just a padded cell without a door.

Which was created from this code:

<sarcasm>
You cubicle is just a padded cell without a door.
</sarcasm>