How it works:
- Version 1: a cab driver/vendor/money changer returns invalid Hungarian banknotes to you as change.
- Version 2: a cab driver/vendor/money changer returns lower value foreign currencies that look similar to Forints banknotes (e.g. Indonesian Rupiah) to you as change.
Places to beware:
- Anywhere (e.g. Budapest Christmas Fair)
What to do:
- Familiarize yourself with the Hungarian forint notes – wikipedia has a list.