Just when you thought it was safe to go back in the water -- Annette and Frankie unfurl their beach blanket, and bingo, you're transported on a new wave of nostalgia, "Back to the Beach," where surf's still up and it's spoofing time. Funicello and Avalon reprise their original roles in a send-up of '60s hormonal comedies that is so relentless it rises above mere camp to '80s regenre.

He's the Big Kahuna and she's the so-called "queen of the sand," and together they are, aptly, as wooden as Tiki Hut totems. And their supersilly sequel is as affably retarded as the original series, with a skimpy plot garlanded in surfer footage and beachside production numbers -- like Annette doing the "Jamaica Ska" with the reggae band Fishbone. The only grit is between the extras' toes.

"Back to the Beach," the feature debut of video director Lyndall Hobbs, finds the former teen idols married, middle-aged and living in Ohio. Frankie is a stressed-out car salesman, and Annette is a housewife obsessed with shoveling Skippy peanut butter into her punky son. Except for this one obsession, "she has been in a good mood for 22 years," reports Bobby, her acid offspring.

Demian Slade, a 14-year-old with a couple of B-movies and a McDonald's commercial under his belt, portrays Bobby, an easy show-stealer who lobs line after great line at these easy cartoon targets. "Girls used to throw themselves at Dad," he explains. "Unfortunately it was 1962 and you had to throw them back. And Mom was the first pinup queen for boys under 12." He narrates the story of their vacation trip to California, where the folks have a tiff while visiting his big sister Sandi (Lori Loughlin) and her surfing man (Tommy Hinkley).

We're never really sure whether we're laughing at or with these sand dabblers, the Mouseketeer with midlife spread and the has-been heartthrob. The gibes about her "hooters" and his "hair helmet" bounce off their blank faces -- either because they don't notice or they've got the comic timing of clams.

Madonna's costume designer, Marlene Stewart, comes up with the retro wardrobe that is the movie's mainstay. "Back to the Beach" offers a fabulous smorgasbord of bikini-clad extras, but Annette, who promised Walt Disney she would never wear a bikini, is still not baring her bellybutton. Wearing enough hair spray to undercoat a Honda, she's demure in flounces that could only have been designed by Minnie Mouse's couturier. Frankie favors long-sleeved spandex shirts and Bermuda-length trunks for his big surfing scene.

Avalon, a one-time top o' the pop-charter, tries a slightly pathetic rendition of "California Sun," painful proof that his voice, such as it was, is a rasp of its former self. The occasion is a visit to a nightclub, owned by former "Hawaiian Eye" star Connie Stevens, playing an old girlfriend who makes Annette jealous. At 44, she's still capable of a world-class snit. Other relics of the '60s and potential relics of the '80s make cameo appearances -- Kookie Byrnes, Don Adams of "Get Smart," the Beaver and his brother Wally, Dweezil Zappa and Pee-wee Herman as a sort of surfboard Tinkerbell who flies in to perform "Surfin' Bird." Best of the oldies is Bob Denver, as a bartender reminiscing about his "Gilligan's Island" stay. He mixes a drink in a pineapple: "I lived with a guy for years. He could take a couple of these and a string and make a nuclear reactor. But he couldn't fix a two-foot hole in a boat."

"Back to the Beach" is strong on lines, but short on story and scenes. And like most lampoons, it goes on twice as long as the material merits. It's deeply vapid, with the emotional consistency of styling mousse.

Still, worse things have washed up on the beach.

Back to the Beach, at area theaters, is rated PG for the bikinis.