If last night's 2 Live Crew performance at the 9:30 club had been a toilet, one could simply have flushed it. As prime exponents of what Spin magazine has dubbed Doo Doo Rap, where bathroom humor is transplanted to the stage and given a beat, the 2 Live Crew has mined fool's platinum with a series of crude, sexually explicit albums. These albums of shouted vulgarities have incurred the wrath of assorted Dudley Do-Rights who have succeeded mostly in padding assorted Crew bank accounts and provoking reams of copy and reels of sound bites for the perpetually desperate media.

Mea culpa.

Lost in the shuffle: the fact that although many millions of people have bought their records, the 2 Live Crew is one of the all-time worst acts, rap or otherwise, that have ever disgraced a stage. Their reputation as a live act must have preceded them because the 9:30 had fewer than 200 customers for the evening's caca-phony ("People know when to stay away," club owner Seth Hurwitz conceded). Those that came -- black and white, and overwhelmingly male -- responded gleefully to Luther Campbell's exhortations, providing a very ungospel-like call and response. Actually, it was closer to cheerleading for Animal House U. Of course, one doesn't listen to this garbage for its deeper meaning any more than one reads Penthouse for its articles.

After a desultory opening set by Poison Clan, the "Baby 2 Live Crew" (no applause, none deserved for an unintelligible, unintelligent display of juvenilea), it was time for the evening's highlights. No, not the Crew, but a video compilation of adult cartoons and a dis-sertation on sexual politics by the New York drag queen Hateful Head Helen. When the Crew came on, it was all downhill.

Depsite their gleeful determination to be offensive, rappers Campbell, Brother Marquis and Fresh Kid Ice offered the scatologies gracelessly while the Me So Horny Girls (not to be confused with the Memphis Horns) offered backup consisting of bumps, grinds, derriere shakes and other gyrations that left little to the imagination. Perhaps imagination was never an issue.

Feebly fueled by audience participation, including that of several women who ventured onstage as instant props, the 2 Live Crew offered up its dim repertoire: "Me So Horny," "We Want Some {Expletive}," "Welcome to the {Expletive} Shop," "Move Something" and, of course, the anthemic "Banned in the U.S.A." For this one the dancers, previously dressed in revealing black strips, came back on in patriotic white outfits that looked like Dallas Cowboy cheerleader rejects. The whole number looked like something Larry Flynt might have come up with had he been sired by George M. Cohan.

As an indication of just how bad the show was, after the 2 Live Crew left the stage before the "Banned" finale, the crowd was not calling for an encore. Their cry was as basic as the music: "Bring the bitches back."

By that point, of course, their heroes had been reduced to zeroes and had somebody had imagination, they could have started up a people's crew with a new theme song, "We Want Some Refunds."

All this doesn't obscure the serious free-speech issues surrounding the 2 Live Crew. After all, a Florida record dealer went on trial yesterday for selling a tape of "As Nasty as They Wanna Be" to an undercover policeman, and the three rappers go on trial next week as a result of their arrest on obscenity charges in a Hollywood, Fla., adults-only club in June. And "Nasty" was the first album declared obscene by a federal judge.

Seeing the Crew live isn't enough to make you believe in censorship, but it's more than enough to convince you that some things should be obscene and not heard.