tag those greenbacks

Would you get in trouble if you tagged a URL on cash?
What if you wrote your twitter name?
Would it help you keep track of your money?
Yesterday I came across this fine stamped bill at a friends place as we were celebrating the greatness that was yesterday. Seems the Black Diamond Riders have stamped their bills. Interesting. I'm sure I'd get haterade from someone if I marked up the bills I use! Is it worth a shot? Hmm.