In the dawn of their Hollywood careers, future Rocky star Sylvester Stallone and the eventual American Gigolo and Pretty Woman star Richard Gere were paired together for the 1974 film The Lords of Flatbush.

But when the film hit theaters, Gere was nowhere to be seen — Perry King had taken over the role Chico because of tension between the two actors. “We never hit it off,” Stallone told Ain’t It Cool News in 2006. “He would strut around in his oversized motorcycle jacket like he was the baddest knight at the round table.”

While both became bona fide leading men in their own rights, their rivalry has endured four decades — often thought to be the source of an unbelievable rumor about Gere and an unfortunate intimate incident with a gerbil (which even received a mention on Saturday Night Live), but also revealed to be the reason for a thwarted fistfight over Princess Diana, according to Elton John.

READ MORE: Inside Princess Diana and Elton John’s Tight — but Often Complicated — Friendship

Stallone pushed Gere out of a car during an on-set lunch

From the start of their time together on the set of The Lords of Flatbush — a drama about Brooklyn street teens also starring Henry Winkler — tensions rose high between Stallone and Gere. “One day, during an improv, he grabbed me and got a little carried away,” Stallone said in the interview about the two simulating a fight scene. “I told him in a gentle fashion to lighten up, but he was completely in character and impossible to deal with.”

But the incident that really pushed Stallone over the edge happened in the back of a Toyota on a cold day in Coney Island. Stallone said that he was eating a hot dog when Gere entered with mustard-covered chicken that was sure to drip.

“He proceeds to bite into the chicken and a small, greasy river of mustard lands on my thigh,” Stallone explained. “I elbowed him in the side of the head and basically pushed him out of the car.”

Though they were on their lunch break, word about the incident quickly got out — and eventually Gere was fired. “To this day, [he] seriously dislikes me,” Stallone said in 2006. “He even thinks I’m the individual responsible for the gerbil rumor. Not true, but that’s the rumor.”

The ridiculous urban legend has gone so far that even Gere has addressed it. “I stopped reading the press a long time ago,” Gere told Metro UK in 2008. “There is an infamous ‘Gere stuck a hamster up his bum’ urban myth. I expect that sort of thing, but when reputable magazines started making up stories claiming I was in a country I had never been to with someone I didn’t even know, I just decided not to pay attention to any of it. It’s a waste of energy.”