Dean Koontz writes a Christmas tale -- The horror author releases his second kid's book, ''Santa's Twin''

Lumps of coal for naughty children, all that nocturnal flying around — isn’t there something just a tad creepy about Santa Claus? Ho-ho-ho benevolence simply must have a dark side. Well, now it stands exposed — in the second children’s book from best-selling horror author Dean Koontz (coincidentally, also a night person). It took Koontz, 51, a mere four days to polish off the 300 rhymed couplets in Santa’s Twin, the funny-gross story of the Red-Suited One’s sicko sibling. ”I have this sort of penchant for writing poetry,” he explains by phone from his Newport Beach, Calif., home. ”Humorous verse is pure fun.”

This twisted ‘Twas the Night Before Christmas began as a plotline in Koontz’s 1993 novel Mr. Murder, whose main character lulled his daughters to sleep by reciting an unfinished poem about Saint Nick’s evil sibling. Some 5,000 fans wrote to the author, clamoring for an ending. Koontz concluded that ”people still like poetry. What they don’t like is modern poetry that’s obscure and self-centered, which they can’t figure out.”

That’s certainly not the case with Twin, in which the wayward doppelganger steals Kris Kringle’s ATM card, fills an unfortunate family’s microwave with 10 pounds of popcorn, and — taking a page from R.L. Stine’s ”Goosebumps” series — replaces carefully chosen gifts with things like toad snot. Fortunately, a team of two brave sisters is at hand to save the day (hint: ”Bob” Claus turns out to be more dysfunctional than evil).

The Clauses’ sootier side stands uncovered. Is that why they’re averse to sunny climes? Actually, according to Koontz, the Claus couple lives at the North Pole only ”because they have to live where there’s no pollen in the air; Bernice [Santa’s wife] has tremendous allergies.” Oh, really? And just how does a warm-weather dweller like Koontz get in the holiday spirit, anyway? ”Santa visits us in his sleigh/soaring over palm trees, beaches, freeways…” quoth the scribe. ”We give him tacos and jalapenos to snack/Santa must like ’em, he keeps coming back.” Santa was unavailable for comment.