I'll forge a rubber check for you
What you scream when someone asks for money for something you already gave them for free. You’re saying you’ll write them a fake check, and even lie about the details, because they’re completely stupid.
You: 'I’ll forge a rubber check for you!' (after your brother asked for $20 for a shirt you already gave him.)
You: 'I’ll forge a rubber check for you!' (because your friend wants money for a pencil you already gave them.)
You: 'I’ll forge a rubber check for you!' (when your cousin asked for cash for a toy you already gave them.)