"There's a word for what you are," someone says to the namesake of "The SpongeBob SquarePants Movie," but it turns out not to be a word that's immediately suggested, like "goofball" or "dork." It's "hugely popular."

All right, so that's two words, but if there's anyone who isn't going to quibble about technicalities, it's the relentlessly cheerful hero of the cartoon series that, with an estimated 60 million viewers, is being touted as "the most watched kids' show in television history."

The sponge that walks like a man, his best friend Patrick the naive (is there any other kind?) starfish, the contrary Squidward and all the quirky residents of Bikini Bottom now have a motion picture to call their own, and that is pretty much a good thing.

Yes, SpongeBob's world is undeniably better suited to the comfy confines of a half hour at home than the more demanding environs of 99 minutes on the big screen. But the experience is such a breath of playful good humor that it's difficult not to be happy it's here. While this is hardly a film you want to force adults to watch, they might not be upset if you did.

No matter what size the screen, SpongeBob's popularity is due to a convergence of factors that work well together largely because they all flow from the sensibility of Stephen Hillenburg, the CalArts graduate who is the show's creator and the film's director.

More so than any of the wildly successful Pixar films, "SpongeBob's" hand-drawn world is aimed squarely at kids. This is an unapologetically silly universe, created with a bright and colorful visual palette, where the jokes are not ashamed to be corny and the characters honestly wonder how you make the transition from being a kid to being an adult. What older viewers like is "SpongeBob's" subversive quality, the offbeat lines (the film has six writers, including Hillenburg) like "You can't fool me, I listen to National Public Radio" that pop up when you least expect them.

Dreamy and a bit surreal around the edges, "SpongeBob" also has a stoner-hipster appeal that is reflected in the presence of musicians such as Wilco and the Flaming Lips on the soundtrack. Though its sensibility is quite different, it occupies that corner of the culture — the one in the crucial middle position of the adult-child continuum — that Rocky and Bullwinkle held down in the 1960s. In changing screen size from small to big, "SpongeBob" has done some things differently. The feature has a live-action prologue and a post-credits epilogue involving a scruffy pirate crew; "Baywatch's" David Hasselhoff, rapidly becoming something of a counterculture icon after appearing in John Waters' "A Dirty Shame," has a key cameo playing himself.

"SpongeBob" also had to come up with a longer plot than usual. It centers on Bikini Bottom's most popular fast-food restaurant, the Krusty Krab, home of the ever-popular Krabby Patty, a place so successful that a branch called Krab 2 is about to open.

Our hero SpongeBob (Tom Kenny) is so fixated on being named manager of Krab 2 he even dreams about it. He tells pal Patrick (Bill Faberbakke) that it's a lock. After all, who else has a wall filled with 374 Employee of the Month certificates?

Plankton (Doug Lawrence), however, has other, more evil dreams. He wants, in no particular order, to make his restaurant, the Chum Bucket, as popular as the Krusty Krab and to rule the world. His nefarious plans soon come to involve our heroes plus the ruthless lord of the sea, King Neptune (Jeffrey Tambor), and his compassionate daughter Princess Mindy (Scarlett Johansson, in her first animation role).

Trying to maintain equilibrium between its origins and its theatrical ambitions, "SpongeBob" balances the TV show's voice talent (including Rodger Bumpass as Squidward) with celebrity names (Alec Baldwin plays a hit man named Dennis). If it's finally no more than an extended version of the show, so light it almost floats away, there are worse sins. Its instinctive, unstoppable cheerfulness can be, as all those millions of viewers have found, something of a tonic if you're in the mood.

'The SpongeBob SquarePants Movie'

MPAA rating: PG for some mild crude humor

Times guidelines: Almost mild enough for a G

Tom Kenny...SpongeBob

Bill Fagerbakke...Patrick Starfish

Clancy Brown...Mr. Krabs

Rodger Bumpass...Squidward

Doug Lawrence...Plankton

Alec Baldwin...Dennis

David Hasselhoff...Himself

Scarlett Johansson...Princess Mindy

Jeffrey Tambor...King Neptune

Paramount Pictures presents a Nickelodeon Movies production in association with United Plankton Pictures, released by Paramount Pictures. Director Stephen Hillenburg. Producers Stephen Hillenburg, Julia Pistor. Executive producers Albie Hecht, Gina Shay, Derek Drymon. Screenplay Derek Drymon & Tim Hill & Stephen Hillenburg & Kent Osborne & Aaron Springer & Paul Tibbitt. Cinematographer Jerzy Zielinski. Editor Lynn Hobbs. Music Gregor Narholz. Production design Nick Jennings. Running time: 1 hour, 39 minutes. In general release.