I've dealt with mentally challenged people before. While they've never been as mentally deficient as a sovcit, I think I can translate. It sounds like they "paid" with paper that they claimed to hold a value, they determined. As an example, to them, a piece of paper with the number 10 written on it is worth $25 American dollars. Or they just outright photocopy monopoly money and use that.

They're filing a counterclaim stating their fake money is real money, and need some case law to help prove it. They can't get that case law, because it doesn't exist.