29 in Japanese can be ni-kyuu, which sounds like niku, and so, the 29th of every month is meat day. 11 is like ii or "nice." So, November 11th is Nice Meat Day. (Not coinsidentally, it's also Super Pochaco's birthday.) The Japanese makers of Kit Kat bars, known for their odd flavors, celebrated with a look at their barbecue idea.
Now, green tea macha, sake, rum raison, pumpkin pudding (for Halloween), beni-imo (sweat potato),and red bean are real Japanese Kit Kat flavors. BBQ, not so much. Don't look for that one at your favorite snack food importer. Note that the Tweet was tagged with "imaginary flavors" and "not for sale."