SOMEONE ONCE called David Rabe's epic play "Hurlyburly" a "horror comedy." That pretty much hits the nail on the head.

The playwright himself has been called "the Neil Simon of desperation and death."

"That's a compliment as far as I'm concerned," says Rabe, 50, who gets his share of laughs among the winces and shudders. Rabe's most memorable plays seem to be set in a jungle of some sort, be it the literal Vietnamese terrain of "Streamers" and "Sticks and Bones," the myth-and-Manson-land of "The Orphan," the wretched Philadelphia of "In the Boom Boom Room," or the heart of darkest Hollywood in "Hurlyburly," which is thumping at the Woolly Mammoth Theatre through Aug. 5.

When "Hurlyburly" was originally produced in New York in 1984, it attracted notice for its 3 1/2 hour length and its cast of Hollywood All Stars: William Hurt, Sigourney Weaver, Christopher Walken, Judith Ivey, Harvey Keitel, Cynthia Nixon and Jerry Stiller. Woolly has cast its own heavy hitters, including artistic director Howard Shalwitz, Grainne Cassidy, Grover Gardner, and returning company member Marty Lodge. And it's still running at a cocaine-paced 3 1/2 hours.

The play creates a ferociously unappetizing (and often profanely funny) impression of its rootless Hollywood characters, centering around Eddie and Phil, casting directors who share their drug-filled house with a couple of other movie-biz maladroits. But it was never Rabe's intent to draw a universal picture of Hollywood mores -- he's concentrating on just this gang of frenetically talkative middle-aged adolescents, on the outs with their wives and their lives, all of them skidding around morally and emotionally.

"You could easily make them lawyers or stockbrokers," Rabe says. "Or mayors."

Rabe knows the turf; recently he worked on the screenplay of "Casualties of War," which he describes as a "mixed" experience.

"But I'm signing up to do another one," he says. "The truth is if I could make a complete living without Hollywood, I would. A lot of it is a way of funding the other work."

Since "Hurlyburly," the other work includes an unpublished novel and three new plays, one of which is, he says, related to "Hurlyburly."

"It's the story of Phil and his wife, and a friend from Phil's past, in and around the same time period," Rabe says. "You don't see any of the other characters. To do it sequentially, you'd do the first act of the new play, then the first act of 'Hurlyburly,' then the second act of the new one. Of the other two, one is really indescribable. and the other one is based on a myth. I might have to hook up with a university to get that one up."

"I kind of hang on to a play till I see it done in a way I can live with," says Rabe, who was never satisfied with the original New York production of "Hurlyburly." That version "tried to put them in a pocket and condemn them," he says, while on the other hand, critics tend to want to sentimentalize the play, in "sort of the 'Lassie syndrome.' "

"Sure, these are not likable guys, they're clearly on the extreme edge of something. But they are not all that uncommon," Rabe says. "It isn't an easy play. It isn't a play that asks you to like it."

Rabe says he's considered coming from his home in upstate New York to see the Woolly production, but he has some reservations. He directed "Hurlyburly" himself fairly recently, in L.A. in 1988, with Sean Penn and Danny Aiello as Eddie and Phil, and he found an accepting audience and a new idea of the play.

"I've got it fixed in my mind and finally out of my system, I think," Rabe says. "I'd be a little afraid of seeing it again, in case it wasn't what I found."

Which brings us, inevitably, to the length of "Hurlyburly."

"I've tried desperately to cut it, and I can't," Rabe says, and sort of sighs. "You cut it and you lose things. In fact, Sean {Penn} was having a terrible time with one moment in L.A., and I went back to the original text, and found a moment that had never made it to the stage anywhere, and I restored it. I just have to live with the fact that it's a long play in a short age.

"Anyway," Rabe says, "I always like to think they're getting more for their money."

By the way, Woolly is extending "Tale of the Lost Formicans," the other play in its summer rep, through Aug. 18. Mary Ellen Nester is replacing Robin Baxter, who is going back into the cast of "Shear Madness" at the Kennedy Center. Call 393-3939.

WHEN THE LEAGUE of Washington Theatres held its elections Monday, the 21 board members re-elected Abel Lopez of GALA Hispanic Theatre as president, and A.J. Pietrantone and Cherry Adler (Library Theatre) as vice presidents. The Washington Stage Guild's Ann Norton is the new secretary and Carolyn Griffin (American Showcase Theatre Company) was voted treasurer. Smallbeer Theatre Company and Potomac Theatre Project have joined the League bringing the roll to 25 member theaters.

WHILE SCENA THEATER, like many other nomadic troupes, is still negotiating with the Church Street Theatre for space for its upcoming season, artistic director Robert McNamara is ready to announce his ambitious plans. McNamara says Scena plans to present Anthony Burgess's new adaptation of "A Clockwork Orange," currently one of the biggest moneymakers at the Royal Shakespeare Company, with a rock score by guitarist Edge of U2. McNamara says Scena will commission its own music and hopes to have the show up by Halloween.

Also on tap is "Mein Kampf" by George Tabori -- it's a newish play about the young Adolf Hitler. Scena will round out the season with a two-play rep of Samuel Beckett's "Happy Days" and Harold Pinter's latest, "Mountain Language," which is a mere 25 minutes long (take that, David Rabe!) and was recently presented by England's National Theatre as a complete and discrete production. Call 549-0002 for information.