There's only so far you can stretch a joke, and the first "Brady Bunch" movie stretched its one joke as far as it could go.

Unfortunately, "A Very Brady Sequel" attempts to mine the same territory. That snap you may hear early on in the film isn't the sound of the film breaking, it's the premise breaking down — as well as the vulgarity barrier, which the film zooms through at the speed of sound with tons of unfunny double entendres.

Like its predecessor, "A Very Brady Sequel" purports to be a parody of the popular series, which is forever in reruns. But as far as parodies are concerned, this one just isn't particularly funny.

Picking up where the first movie left off, the Bradys are still stuck in the '70s while the modern world passes them by. But adding more than a slight wrinkle to things is the appearance of Roy Martin (Tim Matheson), an adventurer who claims to be Carol's first husband, long since presumed dead.

It turns out, though, that Roy is a fake, who killed Roy and who's trying to get his hands on the Bradys' horse statue, which is actually a rare Tang Dynasty treasure worth millions.

While Carol (Shelley Long) tries to sort out her feelings — should she stay with the ever-loyal Mike (Gary Cole) or leave him for the man she thinks she's still married to? — Greg (Christopher Daniel Barnes) and Marcia (Christine Taylor) are considering a fling, since they're no longer related.

That latter subplot is just one of the film's big problems. While the series flirted briefly with an incestuous attraction, it wisely dropped it. Here, however, first-time film director Arlene Sanford bludgeons the audience with shots of Greg drooling over Marcia in a swimsuit, as well as a passionate kiss between the two. Yuck!

Speaking of rehashing the series, the movie swipes bits from the endearingly bad Hawaii episodes and the segment with a Brady boy wanting to be a detective, but without retaining any of the charm. Also, the humor here is even more tasteless and mean-spirited than in the first movie.

Of course, what do you expect, with two writers from Roseanne's series on ABC (Stan Zimmerman and James Berg) and two other writers contributing to the film's disjointed screenplay? With so many meddling hands, "A Very Brady Sequel" feels more like three lame episodes rather than a movie.

Most of the performances are offas well. When the Brady kids sing "Time to Change," they sound as tired as the whole film's concept, and Long seems to be aping her "Cheers" performances rather than Florence Henderson. Only Cole, who again does an eerily Robert Reed impression, and Henriette Mantel (Alice) seemingly escape unscathed.

"A Very Brady Sequel" is rated PG-13 for vulgar, sex-related humor, profanity and cartoonish violence, as well as some drug use (a scene in which Roy eats spaghetti laced with psychedelic mushrooms).