Counterfeit money is certainly a thing, I have a friend that got paid in funny money on a Craigslist deal once and he only figured it out when he when to Walmart and they checked it with the pen.almost got arrested, and he had to go back to every business he visited with the detective.

There are probably better ways to test, but I always use the counterfeit pen when I get paid at my shop.

N21966 - 1973 150L
[Linked Image from ]