A special breed of idiot who firmly believes that you can reverse debt by saying “no, you owe me that”. They usually do that with a brain-gymnastics interpretation of laws and by adding weird markings to legal documents like invoices. Somehow, taping a coin to an invoice and returning it to the sender somehow pays any debt no matter how high. They are instructed by so-called gurus, which ironically refuse any alternative form of payment (e.g. said “coin on the invoice”) except real dollars.