Philadelphia Eagles fans are united by their love for the black and green. Still, nothing quite compares to their display of communal pride for the Birds other than the famous chant that resounds at game-day gatherings throughout the city. The Eagles fight song, “Fly Eagles Fly,” now features the phrase, despite not being part of the original lyrics.

CBS News Philadelphia recently contacted Ed DeLeo, an Eagles superfan who claims he co-invented the now-famous chant during the 1970s. Although the news outlet couldn’t definitively verify his story, his photo collection could provide some clues.

According to DeLeo, in 1975, he and his best friend Pete Black were together at an Eagles game at Veterans Stadium. The two discussed a story they heard about a guy named “Wild” Bill Hagy in Baltimore, Maryland, who would spell body-spell Orioles in the team’s dugout.

“We’re at the Eagles game, and I said, ‘Hey, I read this story about him, and we ought to try that,'” Black said. “After about 15 or 20 beers, the idea gained momentum, and we did it. However, as you saw in the pictures, we had to accentuate it a little bit, and we took off our shirts.”

Admitting they were fairly intoxicated, DeLeo and Black, along with their friend John Livingstone, led what they believe was the first-ever Eagles chant from the top of the dugout at the Vet, where the Eagles and Phillies both played at the time.

As they repeated the act week after week, year after year, the chant started to catch on with fans in attendance.

While the trio’s story can’t officially be confirmed, it does align with information from the team’s public relations executive, Jim Gallagher, who served the Eagles for 46 years.

According to CBS News Philadelphia, Gallagher told Philadelphia Magazine in 2010 that he “vaguely remembers” the chant taking off “in the early ’80s at the Vet.” Could the shirtless trio have created the now-famous chant? What do you think is the real story?