Nowadays, it’s common for hotel rooms to have a slot where you put your keycard in order to power the electricity in the room. Sure, it’s eco-friendly—after all, it eliminates the possibility of leaving your room without turning off the lights—but it can also be a bit of a hassle.

Some hotel key cards are quite sensitive to technology, so if you put it in your iPhone wallet, it’ll deactivate the card’s magnetic strip. Some of them are quite sensitive to scratches or hot sunlight, and others are just finicky and leave you frantically sliding them in and out in mounting frustration. And it can also be a problem if you only have one keycard and you’d like to charge your electronics while you’re out of the room, or, say, keep the A/C on so that it isn’t a inferno when you return late at night.

But one creative Twitter user found a solution to all of your first world woes.

Wanted to charge my battery pack whilst I was I eating dinner, but needed my keycard pic.twitter.com/TsHqihGxTu

— katyagar moonagon (@Oog) March 14, 2018

Katy Moon was staying at a hotel in Dublin and wanted to charge her battery pack while out at dinner. So she stuck a supermarket loyalty card into the slot and, shockingly, it worked!

While the hotel card is sensitive, it seems the room’s slot will take just about any card, even if it doesn’t carry a magnetic strip. Some confirmed that they’ve used the hack themselves, sticking their organ donor cards, Subway discount cards, and railway passes in there with great success.

Now, this technique wouldn’t work everywhere, since some hotels have a more advanced RFID (radio-frequency identification) or NFC (near-field communication) system that will only recognize the actual hotel keycard.

Nonetheless, plenty of people commented saying the hack was a “major game-changer.”

So next time you’re in a pinch and don’t have time to run down to the front desk, it’s worth giving that old Barnes and Noble gift card a shot! And for more travel secrets, read about the two words that will get you an instant airline upgrade.

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