ID Card Madness

You have to wear an ID badge for your new job. But, you are allowed to decorate it any way you like as long as it doesn't cross the line for the professional atmosphere at work (no adult content or gum) and your ID (name, number and photo) have to be visible (otherwise you won't be allowed past security on your next day at work). How far do you go on decorating and what ideas come to mind to make your ID card stand out from the pack?