Usually by the second sequel, the best ideas are exhausted. And usually when it comes to Christmas TV specials, producers delude themselves into thinking audiences crave another version of “A Christmas Carol.”

Credit DreamWorks’ zany “Madagascar” series for ignoring the usual. “Merry Madagascar,” airing at 8 p. m. Tuesday on NBC, is a delightful cartoon adventure with the Central Park Zoo menagerie still marooned on the island of Madagascar.

Just as Alex the lion, Marty the zebra, Melman the giraffe and Gloria the hippo (voices of Ben Stiller, Chris Rock, David Schwimmer and Jada Pinkett Smith) take flight in a hot-air balloon to return home, crazed lemurs shoot them down.

The lemurs mistake the airborne animals for the “midnight marauding red goblin” who drops coal on them. Soon, Santa (Carl Reiner) alights, and they capture him. Everyone knows no good could come from harming Santa.

The special, though only 30 minutes, has the hallmarks of the “Madagascar” movies: It’s fun and clever. Also, the animated animals clearly have back stories.

“He started out as a performer, an actor and a New Yorker,” Stiller says of Alex. “I was very comfortable in his world, a city dweller guy. That was always the way in for me to understand how to be a lion reconnecting with his roots. And the second movie, understanding where he comes from— who was this guy who doesn’t see that he comes from a natural world of lions? I always think of him as a pragmatist, not much experience in doing different things. He keeps the others together. He’s a good guy and gets stressed out.”

Alex has reason to be stressed. Santa’s head injury triggers amnesia, and Alex realizes that if the animals deliver Santa’s gifts, then on his way home, Santa might drop the animals off at the zoo. Meanwhile the reindeer and the penguins bicker, an age-old feud that dates back to when Santa switched poles.

Soon Santa joins the happy animals dancing to the films’ signature, “I like to move it-move it,” and it’s funny to see Santa shake his substantial booty. Reiner laughs just recalling the scene in which he and the other actors were allowed to improvise. “They give us a little latitude,” Reiner says. “When they have Santa skating and dancing, I loved that. I love that he had a bump on his head and he didn’t know he was Santa. They (the creators) are awfully talented and so imaginative. The whole idea is of these animals having left the New York zoo and coming back to do good work and realizing they have a bigger calling than just being mad.”

As they set out on the calling of delivering presents, Melman tries going down the first chimney, gets stuck and whines that he’s claustrophobic. Marty tells him “Now you can be Santa claustrophobic.”

A reference or two may go over kids’ heads, such as when a smitten Private the penguin says to Cupid the reindeer, “We’ll always have Madagascar,” referring to “Casablanca.” But those moments, which just add to the enjoyment for adults, fly by.

Reiner, 87, understands how these movies appeal to all. The tall, gangly actor and writer says this was the first time, in a career that stretches back to 1939’s Works Progress Administration, that he played the jolly fat man. “Being Jewish, it was a thrill to play Santa,” he says.

“Anybody who is going to watch it is going to go away happy,” he says. “If you want to smile, watch ‘Madagascar.’ ”