Wear ALL white. Get some face paint and make your OWN face as UGLY as ever. Do not try and look good today.
Get an old picture frame, or something big enough to fit around your head. Make it look like a picture frame and strap it on to your shirt in anyway possible using tape or glue, and make sure it balances on your shoulders.
When people ask you what you are, say nice and calmly, a mirror! Have fun with this!
Thanks to Michael for this great idea!