McDonald's unorthodox refill practices aren't all that well-known, but they might work to your advantage if you know exactly what to do when it comes to fries.

A viral video showed a McDonald’s customer successfully asking for a fry refill, and now, everyone wants to try it.

Try asking an employee for a refill for your fry container. Free refills aren't an "official" policy, so some locations won’t do it, but many customers claim it’s worked.

Your mileage may vary with this hack, but asking politely for another portion of fries never hurts. After all, the worst they can say is "no."