Crypt Cash

Knott's Berry Farm has issued novelty currency tied to its Halloween Haunt event for decades, but the 2015 Crypt Cash series is notable for using genuine DocuGard security paper — the same substrate specified for check printing and sensitive documents in the United States. That's an unusual materials choice for a theme park souvenir, and it suggests either a deliberate anti-counterfeiting statement or, more likely, a bulk paper source used across their document printing contracts.

The thermochromic ink reacts to heat from a fingertip, a feature rarely deployed on novelty issues. The void pantograph — which causes the word "VOID" to appear when photocopied — has no practical purpose here, which is precisely what makes it interesting.