He was a standup comedian encouraged by Lenny Bruce, a biting satirist celebrated by Kurt Vonnegut, and a swashbuckling drug enthusiast who took a “trip” with Ken Kesey and the Merry Pranksters, dropped acid before testifying at the Chicago Seven trial, and “ingested those little white tabs” with Groucho Marx in Beverly Hills.

In those heady years of 1960s radicalism and experimentation, Paul Krassner was also an irreverent ringmaster of the counterculture, known for battling censorship and decency laws, coining the term “Yippie” to describe his anarchic cohort, and founding the Realist, an influential magazine of satire and social criticism.

An FBI agent once described him in a letter to Life magazine as “a raving, unconfined nut,” a phrase that Mr. Krassner gleefully adapted for the title of his memoir. “The FBI was right,” comedian George Carlin later said. “This man is dangerous — and funny, and necessary.”

Mr. Krassner was 87 when he died July 21 at his home in Desert Hot Springs, Calif. His daughter, Holly Krassner Dawson, said she did not know the precise cause.

In news stories, Mr. Krassner was sometimes described as the “father of the underground press” — a title that once led him to “demand a blood test.” He preferred to call himself an “investigative satirist,” and he filled his magazine with articles grounded in truth but that often veered into fiction.

“I never wanted to deprive readers the pleasure of discerning what is true and what’s not,” he told the Los Angeles Times in 1993. “Our only sacred cows,” he added, “are irreverence and obviousness.”

A former contributor to Mad magazine, Mr. Krassner founded the Realist in 1958 and ran the publication almost single-handedly for 16 years, growing a subscription list of 600 names into a reported readership of about 100,000 that helped lay the groundwork for magazines including National Lampoon and Spy.

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Taglines on the cover proclaimed that it was “the magazine of the lunatic fringe” and “the fire hydrant of the underdog,” and contributors included cartoonist Robert Crumb; authors Terry Southern, Joseph Heller and Norman Mailer; and comedians Bruce, Woody Allen and Richard Pryor.

A 1967 centerfold by Wally Wood, an artist for Mad magazine, showed Disney characters uncharacteristically engaged in sex acts on the grounds of what appeared to be the Cinderella castle. A separate poster, credited to Mr. Krassner and sold through the magazine, featured two of the most incendiary words in the American lexicon: “F--- COMMUNISM!”

Printed in a star-spangled red, white and blue color scheme, the poster was not only “funny as heck,” Vonnegut wrote, but demonstrated “how preposterous it was for so many people to be responding to both words with such cockamamie Pavlovian fear and alarm.”

As a writer, Mr. Krassner was probably best known for crafting a “missing” chapter from “The Death of a President,” historian William Manchester’s 1967 account of the John F. Kennedy assassination. First lady Jacqueline Kennedy had tried to block the book’s publication, and it was released only after several pages were cut.

In a Realist article, Mr. Krassner wrote that Lyndon B. Johnson, moments before being sworn in as president, sexually penetrated Kennedy’s neck wound, possibly changing the nature of the bullet wound. The article infuriated many journalists and politicians, although Mr. Krassner was defiant, saying that the story was “a metaphor for Johnson’s crude character” and introduced some readers to what he viewed as “the coverup of JFK’s assassination.”

The magazine’s journalism, and Mr. Krassner’s writing, was sometimes far from satire. He published early stories by Margo St. James, an advocate for sex workers; covered the trial of a pharmacist arrested for selling condoms; and interviewed a doctor who performed illegal abortions, in the years before the procedure was legalized nationwide.

“From my own experiences as an activist, going back to the early ’60s, there were only two sources of information in the country that we really trusted and that went against the mainstream information. Those were I.F. Stone’s Weekly and the Realist,” political activist Abbie Hoffman later told the Chicago Tribune.

With activists including Hoffman and Jerry Rubin, Mr. Krassner formed the puckish Youth International Party, whose members were known as Yippies. He said he was vacationing in the Florida Keys, smoking “Colombian grass” on New Year’s Eve 1967, when the group began discussing the upcoming Democratic National Convention in Chicago.

They proposed a series of demonstrations near the convention and, by most accounts, settled on the Yippie name for themselves and their supporters after Mr. Krassner began working his way through variations of the word “hippie.” (The term was later echoed by “yuppie,” referring to young urban professionals.)

In Chicago, the Yippies staged theatrical protests and nominated a pig, Pigasus, as their presidential nominee. Police, National Guardsmen and other security forces clashed with demonstrators, and a group that became known as the Chicago Seven — or the Conspiracy Eight, counting initial defendant Bobby Seale — was arrested on charges of inciting a riot.

Mr. Krassner was not charged, and he said that he took a dose of LSD before being called as a trial witness in an effort to sicken his stomach and avoid answering questions. He was still put on the stand, unable to think clearly, and angered friends such as Hoffman, who feared he was jeopardizing their chances in court. (Several of the defendants were sentenced to prison, but the convictions were reversed on appeal.)

“Every individual has a little Yippie and yuppie within,” Mr. Krassner told the Tribune on the 20th anniversary of the convention protests, still yearning for a social transformation that never quite came to pass.

“There’s a Yippie spirit that knows that this is a sadomasochistic society and that some kind of social revolution has to take place to bring about the changes necessary. The yuppies know that, too, but they want to watch the revolution on their VCRs. Sunday brunch. Have a few friends over. I mean, what’s a social revolution for if you can’t have it at your convenience?”

Paul James Krassner was born in Brooklyn on April 9, 1932, and raised in the Astoria section of Queens. His father was a newspaper printer, and his mother was a Russian-born secretary. They signed him up for violin lessons, and he soon demonstrated the talent of a prodigy, performing at Carnegie Hall at age 6.

While onstage, he developed an itch on his left leg and stirred howls of laughter from the audience when he started playing his Vivaldi concerto on one foot, using the other to scratch. “It was the first time he really made people laugh,” his daughter said by phone, “and he really liked that and wanted more of that.”

Mr. Krassner studied psychology and journalism at Baruch College, then part of the City College of New York, but dropped out three credits short of a degree and moved to Greenwich Village. In addition to writing for Mad, he worked at the Independent, a monthly tabloid led by future book publisher Lyle Stuart, who supported the Realist.

“The only humor around then was in Mad and New Yorker cartoons,” Mr. Krassner told the Tribune in 1988, recalling his magazine’s early rise. “So I really had a clear field, almost no competition.” (After the magazine folded in 1974, Mr. Krassner resurrected the Realist as a newsletter from 1985 to 2001.)

Almost from the beginning of his career, Mr. Krassner also worked as a stand-up comic, initially performing under the name Paul Maul and using a violin as a prop. Bruce, an early mentor, advised him to drop the act and simply perform as himself.

Mr. Krassner, in turn, helped edit the comic’s autobiography, “How to Talk Dirty and Influence People” (1965), and received a Grammy nomination for writing the liner notes to Bruce’s six-CD compilation “Let the Buyer Beware” (2004).

After the demise of the original Realist, Mr. Krassner jumped between jobs and assignments, struggling at times to support himself in a world that had grown slightly more comfortable with four-letter words and extreme comic irreverence.

In 1977, he was invited to a Christmas party by Hustler publisher Larry Flynt, who announced that he was resigning his leadership role at the porn magazine after experiencing a religious conversion — and that Mr. Krassner would replace him.

“I know it’s bizarre,” Mr. Krassner told People magazine, “but if God told him to hire me, I ain’t going to argue about it, even if I’m a born-again agnostic.” Mr. Krassner ran articles on Malcolm X and abortion, and was ousted after just six months.

He later hosted a radio talk show under the name Rumpleforeskin; released comedy albums such as “We Have Ways of Making You Laugh” (1996); wrote essays on mescaline, peyote, “toad slime” and other drugs; and published satirical collections as well as his memoir, “Confessions of a Raving, Unconfined Nut” (1993).

His latest collection, “Zapped by the God of Absurdity,” is slated for publication in September.

Mr. Krassner’s marriage to Jeanne Johnson ended in divorce. In addition to their daughter, of Napa, Calif., survivors include his wife of 31 years, Nancy Cain of Desert Hot Springs; a brother; and a granddaughter.

“If I had one thing to tell everybody, it would be: Do it now,” he told Life magazine in 1968, effectively summing up a personal ideology that he maintained for decades.

“Take up music, read a book, proposition a girl — but do it now,” he continued. “We know we are all sentenced to death. People cannot become prisoners of guilts and fears. They should cling to each moment and take what enjoyment they can from it. I do not mean reckless, hedonistic pleasure. There just should not be a dichotomy between doing and being, spirit and flesh, pleasure and principles, work and play, orgasm and love.”