If you like a little sour lemon juice in your holiday eggnog, “Bad Santa 2” just might suit your taste.

This sequel to the anti-sentimental comedy “Bad Santa” — a modern classic from 2003 — reunites its main cast for another round of heartless behavior and low-stooping jokes. Even an R-rated Christmas comedy, though, should offer us a little comfort and joy, something “Bad Santa 2” seems determined not to do.

Billy Bob Thornton returns as Willie Soke, the safecracking Saint Nick, along with Tony Cox as his elfin helpmate, Marcus. When we last saw him, Willie had created an ersatz family with Sue (Lauren Graham), a woman with a convenient Santa Claus fetish, and chubby Thurman Merman (Brett Kelly), a boy with more heart than brains. Thirteen years later, Sue is gone, Thurman is on his own and Willie is back to his hard-drinking ways. The film opens with Willie writing a note and sticking his head in the oven.

It’s electric, unfortunately, which is a good gag but a rehash of Willie’s suicide attempt in the first film. That’s just one example of the way this film tries to repeat or outdo the original instead of starting afresh. Willie and Marcus are once again posing as Santa and elf, this time to steal millions from a Chicago charity called Giving City. There’s another uppity boss, Regent Hastings (Ryan Hansen), and another nosy security guard, Dorfman (Jeff Skowron). Christina Hendricks plays the charity’s manager, Diane, who, like Sue before her, has an inexplicable lust for Willie.

The film deserves credit for bringing back Kelly, now in his 20s, as the angelically dumb Thurman, and for casting the great Kathy Bates as Willie’s sleazebag mother, Sunny. Dressed in ratty shirts and Lou Reed eyeliner, Bates is almost enough to make us glad we showed up. In fact, under the direction of Mark Waters (“Mean Girls”), the cast often hits an impressive stride with its foul-mouthed repartee, written by Shauna Cross (“Whip It”) and newcomer Johnny Rosenthal.

Still, that’s not enough to fully recommend “Bad Santa 2.” The movie tries so hard not to be sweet that it ends up feeling slightly curdled.