Big Mac, fries, and McFlurries aren't the only things you can get at McDonald's.

Customers ordering fast food at the Woodbine Beach McDonald's in Toronto can get a cup holder that folds open into a boombox speaker for your phone.

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The Canadian location is giving out the limited edition cup holder/speakers to celebrate the McFlurry's 22nd birthday, which, FYI, was invented in Canada. Sorry, America, no awesome transformer cup holders for you!

The McDonald's Boombox was a collaboration with the University of Waterloo's Audio Research Group and Stacklab. The goal was to see if they could turn a disposable cup holder into a speaker for your phone.

While the result isn't quite a Bluetooth speaker — there are no electronic bits inside of the Boombox — it still works as an amplifier, increasing sound from your inserted phone's speakers by 101 percent.

The McDonald's Boombox works much like a putting your phone in a cup. Sound is reflected through the cone shape and amplified. Its designers at the University of Waterloo and Stacklab ended up going with a 10-sided cone design that opens up between the bottom of the cup holder.

"When we changed the shape of the cones of the McBoombox, the difference in sound levels was 50 percent," says Janelle Resch, PhD candidate and entrepreneur at the University of Waterloo, in the Boombox's promo video. "When we used the reflective material, you increase the sound level by 43 percent. Inserting your phone increases the sound level by 101 percent."

It's a brilliant way to give cup holders a second life and is the perfect thing to bring to a picnic during summer.

Sadly, the McDonald's Boombox is extremely limited. They're only being distributed on July 28 from 2-7 pm ET, and by the time you read this, they'll probably be out of them. McDonald's, if you're reading this, how about mass-producing them for all your restaurants?