When the Plasmatics say "Dynamite," they're not talking about their music.

Listen to Wendy O. Williams, lead singer for the New Wave group: "I love Cadillacs -- they're real boats, so beautiful, comfortable. I have one, I love them -- that's why I love to blow them up."

It's a Plasmatic specialty. The five-member group (which features a 6-foot-5-inch lead guitarist who looks like an understudy for "Dawn of the Dead," complete with blue-dyed Mohawk haircut and tutu) is an on-stage eve of destruction: They chain-saw through guitars, sledgehammer televisions and radios, fire loaded shotguns into their amplifiers, and even play a little bit of rock 'n' roll.

"We like to show that things are just . . . things," said Williams before the group's Thursday night concert at the Ontario. "People worship 'things.' You work for them and take care of them and these things become your gods. What we do is show that they're just things ."

The band buys its targets in bulk, including guitars and TV sets. "Everything works, everything is new," Williams said. "We call them disposable. We blow up our profits. People ask who pays for them. Our fans pay for them. The more popular we become the bigger our shows will be, the more we'll put into them. This is what gets us off. This is what we're after -- getting off."

Some 10,000 people in New York got off in mid-September when the Plasmatics gave their biggest (and free) outdoor show on Pier 62. With the cooperation of New York police and fire officials, Williams drove a 1972 Cadillac Coupe de Ville loaded with explosives onto a stage laden with explosives. She leapt out just before the whole caboodle blew up and toppled into the Hudson River.

The Rebels Without a Pause came out of the event with hardly a scratch -- and with a film that may well show up on the midnight circuit. All this only two years after the Plasmatics first got together "out of sheer boredom." oBefore that, Williams was a star on the live sex circuit in Times Square. "I specialized in all-girl lesbian acts," said Williams, "but that has nothing to do with what I do now." She objects to critics who have called the act "porno rock." "It infuriates me," says Williams, who performs in a sort of Barbarellia castoff costume, with electrical tape barely covering her breasts. "Heavy metal punk, okay. Acid punk, okay. But porno rock?"

The group's manager, Rod Swenson (an ex-Yalie with a degree in fine arts) first met Williams when he was known as Captain Kink on the lives sex show circuit. One suspects the $30,000 Pier explosion was his scheme. "I was scared to death," Williams says, "but I love the combination of fear and excitement. Sitting through a Plasmatics show and coming out alive gives everybody a group feeling, an instant orgasmic rush. It's 1980s rock 'n roll, which is what everybody's looking for."

The fans do come out: The Plasmatics were the first group to play (and sell out) New York's Palladium without a record contract. After four singles on their own Vice Squad label, they've just put out their first album: "New Hope for the Wretched." Since the beginning, they've been one of the top underground draws on the East Coast. Part of it, says Williams, is that "We have a Living Theater effect, where people come dressed as the band, in butcher jackets and black hoods. Our fans go way out, but I don't think you should ever let your fans get farther out than you are."

At the Ontario on Thursday, the band was merciless -- both dramatically and musically. They chain-sawed the guitar, blasted the amp and so forth. But the effect was less devastating than the music, which sounds like what you hear when you're stuck under an elevated train track in rush hour. Williams has all the range of an air-raid siren, wholly obscuring the lyrics she sings. Songs fly helter-skelter like a pop music demolition derby. Whatever their value as a spectacle, the Plasmatics are better obscene than heard.

The group has a dream: The Great Plasmatic Concert, perhaps somewhere in Nevada. "It'll be free," said Williams. "We'll build a city in the middle of nowhere, with the only way of getting to it and the show being by mule-train. Food and water will be brought in the same way and rationed out."

The concert will run over a couple of days. "As we're singing and playing, the city will be leveled to the ground. When we've run out of songs and we've maybe blown up a blimp overhead with an airplane or helicopter, everyone will have to leave by muletrain. This is what gets us off."

What, no encore?