On Friday, February 20, 1981, Andy Kaufman sat down in a fake restaurant, delivered scripted lines, paused, and then shook himself out of character. “I feel really stupid,” he said.

The other actors—including future Seinfeld co-star Michael Richards—looked confused; the audience hollered. On live television, Kaufman went on to say he felt the sketch (about a pair of stoned couples dining out) was lame and ineffectual. Richards went off-camera to fetch cue cards and tossed them in Kaufman’s lap. Kaufman retorted by tossing water. Someone threw butter. Stagehands pried the performers off one another. The next day, newspapers around the country were asking if Andy Kaufman had lost it.

The show was Fridays, ABC’s attempt to capture the anything-goes feel of NBC’s Saturday Night Live. Debuting on April 11, 1980 to meager ratings, it treaded water with conservative network orders of six or 13 episodes at a time. According to executive producer John Moffitt, Kaufman’s appearance and the ensuing controversy probably bought it an entire additional season.

Kaufman knew the series was ailing, which is why he figured Moffitt would be receptive to his particular brand of comedy. In his stand-up, the performer was more of an antagonist of his audience than an ally: Many crowds had streamed into comedy clubs only to endure Kaufman napping in a sleeping bag or reading earnestly from The Great Gatsby, threatening to start all over again if they interrupted. (Once, Kaufman gave a nightclub a choice: the book or a record. They chose the record. It was the sound of Kaufman reading.)

Kaufman’s avant-garde humor was not for everyone. After multiple appearances on Saturday Night Live, NBC executive Dick Ebersol grew tired of his instigating behavior, declared him “not funny” and effectively banned him from the show. Fridays, however, was happy to welcome an established SNL personality and act as an enabler for whatever Kaufman wanted to do.

After convincing Moffitt to allow him and partner Bob Zmuda to play out a sword-swallowing scene in the intro that would go “awry”—Zmuda coughed up bloody spittle before the show cut to a commercial—Kaufman informed him he wanted to break out of character during the show’s closing sketch. Cast members Richards, Melanie Chartoff, and Maryedith Burrell were all aware of his plans; the crew was not. (There is some disagreement whether ABC had approved of it: Richards says no, while Moffitt maintains they had to go through the station's standards and practices department.)

After the Fridays episode aired, ABC was deluged with letters and calls asking if it was a put-on. To Kaufman’s conceivable displeasure, a network spokesperson told the Associated Press that it had all been staged. A week later, a contrite and tearful Kaufman appeared on the show to “apologize” for his actions in what Zmuda would later describe as his patented glazed-over hostage look.

“This has been a very hard week for me,” Kaufman said. His regular role as Latka on Taxi had been jeopardized, he confessed, and the scuffle had “led to a separation from my wife.” (Kaufman was not married.) While a certain segment of the audience was aware Kaufman was effectively trolling them, another portion probably wondered if he had lost his mind. His parents, who had once taken him in for psychological counseling as a child, might have renewed their doubts.

Fridays lasted only one more year, being forced into a later time slot by the success of ABC’s Nightline; Kaufman continued to confuse people until his death from lung cancer at the age of 35 in 1984. He never quite copped to the skirmish being faked. Talking to People in 1981, he accused ABC of a cover up and denied it was prearranged. “I like the type of humor where nobody knows what’s going on,” he said. “I just want real reactions.”

Six months after the incident, Kaufman appeared on Fridays one last time to profess he was now a born-again Christian. Kaufman was Jewish.