April 5th, 2007 is the second annual CSS Naked Day. If you are viewing this on April 5th then you will see no styling. Any other day it will look normal. A properly written web page should fail gracefully and still be useable by browsers that do not understand CSS. It is the web standards way. 🙂
The idea behind this event is to promote Web Standards. Plain and simple. This includes proper use of (x)html, semantic markup, a good hierarchy structure, and; well, a fun play on words. I mean, who doesn’t want to get naked?. Feel free to see the original reference article for more information.