Your client/wallet detects it and offers a pop-up with registration or forfeiture options. Up to a certain amount (per person, per year) you can probably just p

Your client/wallet detects it and offers a pop-up with registration or forfeiture options. Up to a certain amount (per person, per year) you can probably just pay a small excise tax (less than 100% forfeiture) to 'clean' it. Larger amounts without explanation would mean a visit from the taxman or Justice Department, however.