Here is another installment of exTRAPaganza, our Thursday over-the-top trap series.
A huge pile of coins lies underground, unguarded.
If the coins are taken, each target that carries the coins outwards must make a hard Charisma saving throw every morning. On a failure, they take 1 Charisma damage per 100gp of coins, which can only be restored via Greater Restoration. Once Charisma reaches zero, there is no more reduction until points are restored.
Once outside the cave, the coins cannot be dropped, given away or spent. They will return to the target.
The only way to get rid of them is to return them to their rightful owner, which will require some serious divination magic.