Marijuana is illegal in North Carolina, but the state still profits from its sale. Under state law, anyone who purchases illegal drugs must buy stamps within 48 hours and affix them to the controlled substance. If you’re caught without stamps, you’re still liable for the tax.

No one expects people actually to do this — since 1990, only a few dozen people have bought the stamps, and many of those are thought to be stamp collectors. But the state has collected more than $68 million for failure to display them.