Glenn Piller, an auto-racing enthusiast, has stamped the back of more than $40,000 worth of U.S. currency, from $1 to $100 bills, with simple red-ink promos for his new Web site, www.ArizonaAuto Racing.com.

I'm sure he's not the first one to think of this. Thankfully It's not legal but it's not clear to the feds if it's advertising or not.

Kim Bruce, spokeswoman with the U.S. Secret Service, which enforces laws against misuse of currency, said federal law forbids the use of money for advertising or any changes to currency that makes it "unfit to be reissued." At issue is whether his stamps constitute advertising, because no product is being sold.

azcentral article