Counterfeit anything is fascinating, but I think there's something especially wild about counterfeit money. Maybe it's that we're so motivated to catch counterfeiters because what we consider "real" money is only real in that a government has decided that this is what money looks like. Currencies are just pieces of paper (or plastic or metal) that we've all agreed have a specific value. If you can make such a good fake that 99 percent of people are fooled, you've kind-of-sort-of made real money—you can use it to buy things, so it has value. Until someone catches on, at which point it becomes worthless in an instant. And in the end, there's something kind of silly about the idea that some pieces of paper get to have value and others don't.