Heineken is tapping into the lovely Christmas tradition of singing carols with a new fun experiment that invited non-professional singers to perform in front of a broad audience. The challenge dubbed Carol Karaoke comes as part of the brand’s U.S. holiday campaign taglined “Open Your Celebrations,” which continues Heineken’s global marketing effort “Open Your World.”

Heineken teamed up with Wieden & Kennedy New York for the experiment that put a small group of unsuspecting friends in a “will you or won’t you” moment at a karaoke party. They all arrived in a small VIP room to sing a karaoke version of Christmas classics “Jingle Bells,” “Deck the Halls” and “The 12 Days of Christmas”—but the experience turned to be not as private as they had expected.

A few seconds after they chose the song, the friends suddenly discovered that that space was a recording room, and the singing could be heard by thousands of people in the streets, stadiums, and even cars. Although they could decide to stop singing, many of them chose to continue the public performance.

“With Heineken Carol Karaoke, we wanted to see if people were willing to cross their borders by challenging them to sing a carol they may not know to an audience of thousands of strangers,» said Colin Westcott-Pitt, VP Marketing, Heineken. “They had to make the decision to sing in mere seconds, and we found some real holiday heroes.”

According to the Heineken Karaoke Survey, conducted earlier by Wakefield Research among 960 U.S. adults ages 21+, the songs “Jingle Bell Rock” (31%) and “Winter Wonderland” (20%) top the list of Americans classics list.

Additionally to the karaoke experiment, Heineken USA has launched out-of-home displays, point-of-sale materials, four limited-edition bottles (view them above) and promotional Heineken Lager 12 packs. Each of the labels features a design that “celebrates a unique Heineken milestone, including the brand’s origins.” The marketing effort is also supported by a TV spot that features dozens of green Heineken bottles, popping up their caps, and forming a green map of the world.