Fool's Gold: Cursed Money for In Game Misers

From publisher blurb: Fool's gold is just that, gold that makes you foolish. These cursed coins were created by the First Bank of WareHave as a deterrent to thieves and cutthroats who would frequently target the bank and its shipments of gold. Often a large coin worth at least 10 gold pieces in weight alone, Fool's Gold has a cumulative effect. The more you take, the more foolish you become.