SubGeniuses nationwide poured into Sherman, N.Y., last week for an end-of-the-world orgy. On a clothing-optional campground, followers of this Dallas-based church have already indulged in blood wrestling (instead of mud wrestling), mass marriages (one couple, hundreds of ministers), poorly played music, and lots of sex (in preparation for the extraterrestrial nymphs). But come 7 a.m. tomorrow, eyes will turn upward for the fire in the sky. All aboard for the Promised Land.

''There will either be sex and bowling and real good meals and massages - like on a cruise ship,'' Cambridge resident Dr. Y Foo said of the flying-saucer paradise, ''or there will be personal servants who will let you have whatever you want, like if you want to be surrounded by 20 Cindy Crawfords. Or we'll be put in cement cages, and we'll be chopped up to make us taste better as people burgers.''

Hundreds of Bostonians and area college students, particularly MIT techies, have denounced normalcy and invested blind faith in Bob. Not to sound blasphemous, but Bob isn't even real. He's merely a 1950s-esque clip-art icon of a well-groomed, waxy-smiled man with a pipe. For $30, anyone can register to become a card-carrying minister. Triple your money back, the church promises, if you die and realize you haven't been eternally saved.

In simplest terms, the church uses parody and humor to spread the messages of carpe diem and free thinking. Any new members who have taken Bob too literally are ''deprogrammed'' by church veterans, who suggest they reread the books as satire. With no-nonsense fervor, however, the church urges individuals to find ''slack,'' the freedom to pursue happiness and escape conformity. Believers vow death to the Conspiracy - the government, the Man, the job, Starbucks coffee, or anything else that infringes on one's Bob-given right to slack.

Parody or not, some members go to great lengths in service to church. The Irreverend Friday Jones of Waltham, for instance, quit her job at a video store in the name of Bob. A week before she left for New York, Jones was sauntering around Central Square with an uncanny glaze on her face. Storm clouds had cleared. The sun was beaming and so was Jones, with a tranquil smile and faraway gaze. ''You just think, `This might be the last time I walk down this street on a nice, sunny day,''' said Jones, who, like Foo, declined to give her real name.

Nearly 20 years of the church's twisted prophetical ramblings will climax tomorrow. July 5, 1998, was named doomsday 18 years ago, when Bob dictated his message to ''sacred scribe'' and cofounder Doug Smith, a.k.a. Reverend Ivan Stang of Garland, Texas. Stang has since compiled Bob's message into books, pamphlets, and a Web page at www.subgenius.com. ''Just like in other religions, it's not so much that we love Bob; it's the idea of everyone else going to hell,'' Stang said.

Calling Bob the world's greatest salesman, SubGeniuses have eagerly bought into his spiel. More than 200 believers packed the April ''devival'' party at the Middle East in Cambridge. Loads more have recently jumped on the bandwagon because of the hove ring now-or-never deadline, Jones said.

But the church's final countdown has alarmed some outsiders. Kurt Kuerstiner of Tallahassee has designed a Web site titled ''Please Help Expose Bob!'' and has sent literature to schools and police departments, warning them of the cult's apocalypse. He fears a troubled loner may take the joke too far. ''The deadline is coming up, and I'm afraid someone's going to be dead on that deadline,'' he said.

That SubGenius books are found in the humor section of Barnes & Noble disguises the church's sinister hatred for the ''normals,'' Kuerstiner said. ''The church claims to be a parody,'' he said. ''That's why someone is afraid to come out against this thing; it looks like he doesn't get the joke. It's the ultimate camouflage.''

Church members insist they are not the next Heaven's Gate. Rather than staging mass suicides, they would rather board the spaceships alive. Explained Bevilacqua: ''The sex goddesses aren't going to be that much fun without our bodies.''