I took a couple of minutes with Photoshop and, thanks to a randomly-Googled tutorial (from CSS Creme design site) I put together a colorful little badge that people can use instead. If they don't want to create their own.
Use the following HTML code to insert the image in your own posts
<img alt="Trigger Warning" title="Trigger Warning" src="http://2.bp.blogspot.com/_cDVtg63O_Jc/S8VzA5JP2pI/AAAAAAAAAHs/_HQlWsz39ro/s1600/TriggerWarning.png" style="float: left; margin: .5em;"/>
That will float the image on the left-hand side of whatever paragraph you insert it in, allowing the surrounding text to flow around it.
I do think it's a good idea to replace the text with a graphic. (The HTML title and alt-text ensure accessablity on alternative browsers.) Feel free, of course, to make and use your own instead.