The Molson Canadian traveling beer fridge is once again on the move. It's also once again tempting Canadians with the promise of free beer—but this time, they have to work a little harder for it.
In honor of the upcoming Canada Day holiday, Molson Coors is moving a refrigerator stocked with Molson Canadian lager around the country. To unlock the fridge, all the person needs to do is sing a song—specifically, the Canadian national anthem.
Belt out a perfect rendition of "O Canada" and the beer fridge opens, giving access to the bottles of Molson Canadian inside. If a mistake is made mid-anthem, a buzzer sounds and free beer hopefuls are forced to start all over again.
An earlier version of the Molson Canadian stunt required scanning a Canadian passport in order to unlock the fridge. That refrigerator debuted in Canada last year and made a stop at the Canada Olympic House at the Winter Olympics in Sochi earlier this year.
—By CNBC's Tom Rotunno.