Here’s your viral video for today. Apparently engineer Evan Long has managed to combine Square’s credit card reader hooked up to an iPod touch to play back reel-to-reel audio from an old-school cassette player. We’re down in the comments…

As noted by Gizmodo, the Square-iPod touch combo really works as advertised, turning your device into a rudimentary vintage cassette player:

The magnetic stripe reader on the Square basically works exactly like the magnetic read and write heads on an old school cassette player or reel-to-reel machine.

But to make this work, you’ll have to make sure you’re using the older version of the Square which doesn’t encrypt the data it reads.

And to ensure the tape slides easily through the reader, you’ll also have to open it up and loosen the read head.

Long explains that since the headphone jack on most iPods and iPhones doubles as a microphone input, that’s what the Square reader is using to transfer data.

Pretty ingenious, no?

I don’t know about you, but this hack scores pretty high on my list of the World’s Most Unusual Tweaks.

What do you think?