voucher goblin
When you cash out at a casino, often times the machines will not give change and instead print out a voucher for the change. Most people just grab their cash and walk away. Voucher goblins hope for this, and hover by the cash out machines at casinos hoping to collect these abandoned vouchers and scrounge up enough to finally make a bet of their own.
You can tell the economy is in shambles when there's more than one voucher goblin camping out by the cash out machines.