Related Clues:

• Subject of this puzzle's theme
• Cash alternative
• Debt note
• Loan letters
• Payback without the payback
• Chit letters
• Note from someone shy?
• Collector's item?
• Poker night marker
• I.O.U.'s
• Payer's promise
• Debtor's promise
• Promising letters?
• Debtor's onus
• Poker pot paper, perhaps