During the second quarter of the Harvard-Yale football game on November 20, 1982, a big black balloon with “MIT” written all over it suddenly emerged from the Harvard Stadium field. “The two teams were lined up when suddenly our attention shifted toward the sideline,” remembers MIT Museum science and technology curator Deborah Douglas, who was there. “That’s when we saw it. Everyone was trying to make out what was written on the balloon. Some of the Harvard police seemed to draw their guns. And then suddenly it exploded.”

The field was quickly repaired, and Harvard went on to rout Yale, 45-7. But in the stands, the focus remained on the balloon. “There was quite a stir,” says Douglas. “Everyone was talking about it.” CBS’s Brent ­Musberger mistakenly announced on television that a bomb had floated down from the stands and exploded, leaving a three-foot crater. “It was one of the most unbelievable things I’ve ever seen,” WBZ-TV anchorman Bob Lobel told Harvard magazine’s Craig Lambert in 1990. “It had to be the greatest college prank of all time.”

As the hack approaches its 25th anniversary this fall, Lobel’s assessment is proving accurate. No history of Ivy League football is complete without photos of the MIT balloon and a description of the incident. “This is the only hack that I have consistently been called about during my eight years at MIT,” says Douglas, whose curatorial responsibilities include hacks. “It is certainly in the top five hacks, and I rank it the greatest. It transcended ­categories and connects with the past better than almost any other hack.”

The hack was conceived in 1978, after Delta Kappa Epsilon (Deke) fraternity brothers buried plastic tubing that would ooze yellow paint spelling “MIT” in Harvard’s field. When groundskeepers discovered and disabled the tubing, the would-be hackers revised their plan. They designed and built the balloon apparatus in 1978 and ‘79 but graduated without deploying it. In 1982 their successors at the fraternity “found out about it,” says David Husak ‘84, who helped with the balloon hack. The brothers installed the balloon apparatus during at least nine predawn trips to Harvard Stadium. “About 20 guys participated,” Husak remembers. “We’d go in at 2:00 a.m., with camo paint on and lookouts in the [stadium] towers.” An electrical-­engineering major, Husak was responsible for the wiring. “Some of that wiring is probably still there” he says, laughing.

“I found the irrigation control board and wired [the device] into an empty circuit breaker,” he says. But on game day, the balloon didn’t deploy. A Deke talked his way past a Harvard policeman, got into the electrical room, and pulled every circuit breaker. One set off the device, and the rest is history.

Perhaps it’s the idea of hackers taking over, even temporarily, a stadium with tens of thousands of people that makes this hack so intriguing–and unlikely to be repeated anytime soon. “There is a skittishness in the culture, a feeling that pranks are not benign,” says ­Douglas. “I think it could be done [again], but I suspect it would be received very differently.” ­Harvard director of athletic communications Chuck Sullivan agrees, recalling a foiled hack at the 2003 ­Harvard-­Yale game that “effectively shut the Yale Bowl and the city of New Haven down for 90 minutes.” The New York Times reported that a “Harvard banner that seemingly carried a not-so-friendly message” was designed to unfurl from the scoreboard, but instead “shut down parking lots for hours and kept spectators outside the fence an extra hour.”

“In light of heightened sensitivity toward remote devices in large stadiums,” says Sullivan, “I don’t think we’re terribly interested in revisiting [the balloon hack]. It will go without a mention in our game-day materials this year.”