Let's get one thing clear: "The Rocky Horror Show," now playing at the Woolly Mammoth Theatre, is DEGENERATE FILTH! Furthermore, it commits the unpardonable sins of being SILLY and NOT TAKING ITSELF SERIOUSLY!

Anyone who goes to this little shop of hormonal horror should check his adulthood at the door. When was the last time you went to the theater and were frisked for contraband food and squirt guns before you could sit down? Have you ever wondered what they sell in those sex shops with names like the Pleasure Chest? (Not that I have, of course.) You can see half their inventory on this stage, and I mean more garter belts than Victoria's Secret ever keeps in stock.

There's an old saw that whenever an actor performing for children senses the audience is dozing, all he has to do is yell "underwear!" and fall down to get the little buggers' attention. This show doesn't just yell underwear -- it celebrates it.

This show -- the word "play" hardly seems to fit in the classical sense, although it certainly does in the nonsensical sense -- was authored by an Englishman named Richard O'Brien, who admits to misspending many nights of his youth watching B-grade horror movies. Dare we suspect that recreational chemicals also figured in the creation of this madhouse?

At any rate, the musical opened in a small theater in London in 1973 and played for seven years. In 1975, some weirdo released a movie version, which is called "The Rocky Horror Picture Show," which is patronized to this day by the sort of people who like to go to movies at midnight and yell at the screen. For some, the movie has become a peculiar sort of ritual, like fraternity boys swallowing raw eggs and vodka. The play bombed on Broadway (this is not the ticket for the expense account crowd) but has lived on, like a Mousetrap that refuses to quit, in theaters around the country -- and now Washington, where it opened Friday.

Jeff Church, the director of this production (it came as no surprise to learn he also has a job directing children's plays at the Kennedy Center), says the movie audience in "degenerate Georgetown" has gotten "antisocial and sloppy" and THIS production is the real thing -- as hominy is to instant grits, as cotton is to polyester, as Coke is to bilge water. It is said the tradition of yelling at the screen began on Staten Island when a kindergarten teacher named Louis Faresse yelled at the character Janet when she put a piece of newspaper over her head to ward off the rain. He said, "Buy an umbrella, you cheap {rhymes with witch}.

I did not make that up.

So let's examine the notion of the Real Thing. Oh wait -- is someone out there wondering about the plot? Do I have to tell the plot? Just hang on, I'll get to it.

Now, is this the Real Thing? Yes -- and no. Certainly, at least to my biased, slanted, narrow mind, it seems mighty strange to think of people interacting with celluloid. (In the interest of full disclosure, I have to admit that I have never seen the movie and DON'T WANT TO, but I did at least 17 times walk past the theater in London where the original show was playing.) Yelling at a movie screen seems like drinking decaffeinated coffee. But yelling at real people 10 feet away from you -- now that's healthy and interesting. I think.

Here's the No part. This play introduces, delightfully, the notion of anarchy. They have not merely eliminated the fourth wall, they have chewed it up and spit it out. The audience is expected, even encouraged, to throw things onstage at appropriate moments and to yell rude, even lewd, comments at the actors. For example, when the character of Riff-Raff calls Dr. Frank 'N' Furter "master," you're supposed to yell "bator." That's a mild one.

This is the sort of thing Washington could use more of. But -- here it comes -- Woolly Mammoth has decided to control the anarchy, for reasons it alternately cites as the safety of the actors (did anyone ASK them to put on kinky underwear and get on a stage?), the ubiquitous-but-never-seen-on-this-planet "fire marshal," and that favorite scapegoat for everything -- RATS. Give me a break. They're worried about rats? Have they taken a look at what's onstage already? And haven't they heard of vacuum cleaners?

Anyway, you have to use only the theater's pre-approved prop kit, which you can buy for $3. It contains confetti to throw at Brad and Janet instead of rice; a piece of newspaper (why it's the Cleveland Plain Dealer I don't know; isn't a certain well-known Washington paper good enough for them?); a tiny flashlight to turn on when the cast sings, "There's a light over at the Frankenstein place"; surgical gloves; foam toast to throw when the narrator says, "Ladies and gentlemen, a toast!"; noisemakers; playing cards; and a chart of dance steps for the rollicking "Time Warp." A pretty good deal for $3, but it still feels like someone trying to control your spontaneity.

I guess that says something about Washington. We want to let down our hair, but only with bobby pins in our pocket. We want to have fun, but let's not make the fire marshal mad at us. Sometimes it seems that everyone who moves to this town was the president of the junior class somewhere else.

Oh well, there's still a lot of ridiculous amusement to be had here, if you can handle priapic humor and pan-sexual horseplay. The thing is, despite the aura of decadence, there's a jolly innocence about it, like kids playing dress-up. It's just that what they're dressing up in is drag. Because for all the declamations of sexual liberation, of adhering to the "do it if it feels good" ethos, they really are sending up kinky sex.

Dr. Frank 'N' Furter (played with relish, and mustard, by Grover Gardner), looks like Rosalind Russell after a shopping spree at Frederick's of Hollywood, all black fishnet and leather, sparkly false eyelashes and dangly earrings. Rocky Horror himself, a blond boy toy Furter has created (a muscular Chris Lane), has a scanty costume that gives new meaning to the concept of codpiece. The only conservatively dressed creature is the hunch-backed Riff-Raff (Michael Chaban, superbly menacing), who wears a black robe and is into incestuous "elbow sex" (that is, touching elbows).

The entire cast is wonderfully loony, the set -- especially the frieze of baby dolls -- appropriately tacky, and the costumes a tour de force by Jane Schloss Phelan. The music, while not exactly Rodgers and Hammerstein, is lively and heavily influenced by early rock-and-roll, which is fine with me.

The only mistake Woolly Mammoth has made is scheduling this for such a short run -- through Dec. 2. I bet the theater could run it longer and make some much-needed bucks.

Did I forget the plot? Oops, sorry. This is too long already. You'll just have to see it yourself.

The Rocky Horror Show. Book, music and lyrics by Richard O'Brien. Directed by Jeff Church. Set, Keith Belli; costumes, Jane Schloss Phelan; lighting, Kim Peter Kovac; choreography, by Beth Davi;, music direction, R.L. Rowsey; props, James Hardison. With Grover Gardner, Michael Chaban, Jennifer Mendenhall, Robin Baxter, Nanna Ingvarrson, Steven Schmidt, Rob Roy, Chris Lane, Richard Salamanca, Soshana Beth Gold and Rick Hammerly. At the Woolly Mammoth Theatre through Dec. 2.