It’s Christmas Eve in Japan. Little boys and girls pull on their coats, the twinkle of anticipation in their eyes. Keeping the tradition alive, they will trek with their families to feast at … the popular American fast food chain KFC.

Christmas isn’t a national holiday in Japan—only one percent of the Japanese population is estimated to be Christian—yet a bucket of “Christmas Chicken” (the next best thing to turkey—a meat you can’t find anywhere in Japan) is the go-to meal on the big day. And it’s all thanks to the insanely successful “Kurisumasu ni wa kentakkii!” (Kentucky for Christmas!) marketing campaign in 1974.

When a group of foreigners couldn’t find turkey on Christmas day and opted for fried chicken instead, the company saw this as a prime commercial opportunity and launched its first Christmas meal that year: Chicken and wine for 834 2,920 yen($10)—pretty pricey for the mid-seventies. Today the christmas chicken dinner (which now boasts cake and champagne) goes for about 3,336 yen ($40).

And the people come in droves. Many order their boxes of ”finger lickin’” holiday cheer months in advance to avoid the lines—some as long as two hours.

The first KFC Japan opened in Nagoya in 1970 and quickly gained popularity. (There are now over 15,000 KFC outlets in 105 countries and territories around the world.) That same year, at the World Exposition in Osaka, KFC and other American fast food chains like McDonald’s were met with great market testing results and helped jump start the westernized “fast food” movement in Japan. After the big commercial push in ’74, the catchphrase “Christmas=Kentucky” paired with plenty of commercials on TV caught on.

The “Americaness” and simplicity of the message rather than any religious associations with the holiday is what makes it appealing. The Financial Times reports:

“Japan is well known for taking foreign products and ideas and adapting them to suit domestic taste, and Christmas is no exception. A highly commercialised and non-religious affair, lots of money is spent annually on decorations, dinners and gifts. KFC is arguably the biggest contributor, thanks in part to its advertising campaign. ‘One of the reasons the campaign lasted so long is that the message is always the same: at Christmas you eat chicken,’ said Yasuyuki Katagi, executive director at Ogilvy and Mather Japan, the advertising agency.”

These days, KFC records its highest sales volume each year on Christmas eve. Back office staff, presidents and execs come out to help move the lines along. Fried chicken and Christmas have become synonymous: KFC’s advertisements feature major pop cultural figures chomping on drumsticks, the company website even has a countdown until Christmas.

And this year, the company launched a campaign that takes the holiday hype to new heights. From December 1 through February 28 passengers on select trips between Tokyo and eight U.S. and European destinations can enjoy KFC in-flight.

But Japan’s love of American fast food does not dim with the Christmas lights once December 25 has come and gone—KFC’s ability to take it’s traditional foods and adapt them to Japanese culture has made a bucket of chicken a meal worth having year round. This April, they opened a three-story restaurant at the south entrance of Shimokitazawa station in Tokyo which offers the company’s first-ever, fully stocked whiskey bar—what their website says gives visitors a taste of “Good ‘ol America.”

Though, if you ever find yourself in Japan and not in the mood for fried chicken, Wendy’s Japan offers a $16 foie-gras-and-truffle burger.

Read more articles about the holidays in our Smithsonian Holiday Guide here