In one of the many surreal, WTF moments in the new Showtime series “Kidding,” the beloved children’s TV show host played by Jim Carrey enters a room and sees his sister has created a giant, papier-mache head of … himself.

He puts the enormous, mascot-esque, fake head over his actual head and says something chilling, something made even more disturbing because it comes from inside that eerie plaster head with the frozen smile.

By then, we’ve been conditioned to expect the unexpected from this unique and wonderfully bizarre show. And yet, we’re continually surprised.

I’ve seen the first four episodes of “Kidding,” which premieres Sunday. Midway through Episode One, I wondered where this thing was going and doubted whether I should care. By the end of Episode Four, I was keenly anticipating the next chapters.

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Dave Holstein (“Weeds”) is the creator of “Kidding” and deserves all due credit for inventing this strange waking dream of alternately darkly funny and profoundly melancholy ruminations about life and death (mostly death).

But the series also marks a reunion of Carrey with his “Eternal Sunshine of the Spotless Mind” director Michel Gondry, and once again they bring out the best in one another.

And, as was the case with “Sunshine,” we’re dealing with the central theme of a man with a shattered heart who is in danger of becoming irreparably broken.

Carrey is Jeff — known to multiple generations of TV viewers across the land as the host of “Mr. Pickles’ Puppet Time,” which originates from the PBS affiliate in Columbus, Ohio.

Every day, the perpetually cheery Mr. Pickles interacts with a motley collection of puppet characters, performs upbeat little skits and sings catchy songs, all designed to encourage the kiddies out there in viewer-land to believe in themselves and embrace the joys of life and all that sunshine-y jazz.

Off-camera, Jeff is spiraling ever deeper into a vortex of unbearable sadness.

It’s been a year since Jeff’s young son Phil was killed in a freak traffic accident. (We eventually see the details in a flashback set to the title track from “Jesus Christ Superstar.”)

Since then, Jeff’s wife Jill (Judy Greer, terrific as always) has split from him and has taken up with another man (Justin Kirk), a smarmy jerk who takes Jeff for a fool.

Jill (Judy Greer) wants out of her marriage with Jeff on "Kidding."

Jill (Judy Greer) wants out of her marriage with Jeff on “Kidding.” | SHOWTIME

Jeff’s son Will (Cole Allen), twin brother of Phil, is acting out by hanging out with the wrong crowd, getting high all the time and cringing at the very idea of hanging out with his father.

In the meantime, Jeff’s sister Deirdre (Catherine Keener), the mastermind behind all the puppet creations on the show, is in the throes of a serious marital crisis while her daughter goes through an alarming rebellious phase. And Jeff’s father Seb (Frank Langella), who runs the home station for “Mr. Pickles’ Puppet Time,” is considering replacing his son with an animated version of Mr. Pickles — because after all, a cartoon Mr. Pickles will never grow old and won’t bring his problems to work, will he?

Langella is a master of deadpan comic timing as Seb, who reminds Jeff the franchise is worth more than $100 million in “edu-taining” puppets, toys, DVDs, books, etc. Seb sneers when Jeff calls the viewers “friends,” but he encourages Jeff to meet and hook up with one of the many grown women who have sent him fan letters, saying they’d like to personally thank Mr. Pickles for being such a positive influence on their lives.

Jeff’s father (Frank Langella) also runs the TV station where he works on "Kidding."

Jeff’s father (Frank Langella) also runs the TV station where he works on “Kidding.” | SHOWTIME

(In one beautifully creative montage, we see how a crack-addicted woman happens upon an episode of “Mr. Pickles’ Puppet Time,” is reminded of the optimistic young girl she used to be — and turns her entire life around.)

Greer is equally wonderful as Jill, who tells Jeff being married to Mr. Pickles is like being Mrs. Santa Claus. Nobody cares about Mrs. Claus!

And then there’s Jeff/Mr. Pickles, and what a pair they make. Jeff isn’t much more sophisticated than his TV alter ego. He has the world’s oldest mobile phone, he’s unaware of the meaning of commonly used vulgar terms and he often visits a hospital cancer wing (named after him) and will do just about anything to cheer up the patients.

But Jeff also has a hair-trigger temper and is engaging in stalker-like behavior in his efforts to win back Jill and keep tabs on his son. As his father puts it, Jeff is starting to sound like the kind of guy who climbs a tower and starts firing at random.

Carrey is brilliant. With the possible exception of the late Robin Williams, there’s no other actor of the last 30 years better suited to playing this type of man/child character who engenders such good will and displays near saintly qualities — but also gives us the heebie-jeebies.

‘Kidding’

1⁄2

9 p.m. Sundays on Showtime. The premiere episode is available for free viewing on YouTube, Facebook and sho.com.