When Hanukkah falls earlier in the calendar, apart from the traditional Christmas season, Kreider said, "it's usually the kiss of death from a retailer's perspective. But with Thanksgivukkah, you're going to be with relatives, what are you supposed to do? You're with 10 nieces and nephews. You're not going to give them a little something? This has brought Hanukkah to the forefront."
How rare Thanksgivukkah is remains a topic of debate, because it's a question of analyzing and predicting the part-lunar, part-solar Jewish calendar and the Western calendar, which is lunar. Some experts say the convergence hasn't happened since 1888 and won't again for more than 70,000 years. Others say it happened in 1918 and will again in 2070.
The bigger debates are about food — and what constitutes something really "Jewish" and something really "American." For example, because the original story of Hanukkah involves a small amount of lamp oil miraculously lasting eight nights, oil is the key to the holiday — thus the classic deep-fried potato latkes and doughnuts. But what about a deep-fried turkey? Is that legit?
Tina Wasserman, author of several popular cookbooks on Jewish food, said people worry too much about messing with food traditions.
"Our food tells stories. The question is, did the story come first and create the food, or does the food come first and create the story?" she said. She is advising the torrent of people with Thanksgivukkah questions on food blogs and her Facebook page that if they're uncomfortable merging a recipe, just include two classics — like mashed potatoes and latkes.
"This is the one holiday when you can put another carb on the table and no one will complain," she said.
In some places, the merger wasn't positive. Jewish customers online reported seeing fewer Hanukkah items in grocery stores because shelves were being taken up with Thanksgiving items. The Kosher Pastry Oven in Silver Spring, which usually makes a killing on their pecan and pumpkin pies on Thanksgiving and then a few weeks later on their doughnuts, said business suffered a little as customers had to choose.