The video, posted online anonymously, picks up mid-argument, as a woman twirls onto her fork spaghetti from a takeout container and a passenger across the aisle chides her.
"What kind of animals eat on the train like that?" says the woman across the aisle.
The diner snaps back with an epithet, and the exchange quickly degenerates into a fistfight.
"Chill out!" shouts a man as he tries to pull apart the two combatants.
The video has touched a nerve in a stressed-out city where the commutes are difficult and no perceived slight goes undocumented, thanks to cellphone video cameras.
On Internet sites, hundreds of viewers of the spaghetti skirmish debated the smell and the spilling of subterranean snackers. One YouTube contributor mixed video of the fight with scenes from the violent 1983 Al Pacino crime drama "Scarface."
Some New York commuters called for a subway system ban on food, like the ones enforced in Washington, San Francisco and other cities. The Port Authority Trans-Hudson trains, which run between New York and New Jersey, already prohibit eating.
"I think it's nasty when people eat," said Sam Ramos, as he rode a 5 train to the Bronx. "They should go somewhere else."
But at the other end of the car, John Augustine dug into a cup of chili and said people should mind their own business.
"People will fight about all kinds of things," Augustine said. "Are we going to legislate against every one of them?"
Littering, playing loud music and smoking are prohibited in the subway system. On Wednesday, the chairman of the Metropolitan Transportation Authority, which runs the city's subway and bus system, said police have bigger problems to deal with than patrolling the trains for chowhounds.
"We all have a responsibility to treat our subway system and our fellow riders with respect," chairman Jay Walder said. "This is a system that carries 5 million people a day, and I'm not sure that a ban on food is really practical or enforceable."
MTA board member Andrew Albert said such a rule would cut into food sales at newsstands, which pay rent to the agency. But another board member, Doreen Frasca, suggested the MTA should impose the rule on the Manhattan Second Avenue line, which is under construction, as a pilot program.
Some riders recently have taken enforcing subway etiquette into their own hands. Last year, artist Jason Shelowitz posted dozens of official-looking signs in stations warning commuters not to clip their nails on the subway.
"The sound is incredibly annoying and the nail bits go flying all over the place," the signs said.
"Also, keep your finger out of your nose," another sign said.
A Brooklyn graphic designer, Elizabeth Carey Smith, kept track of how many times fellow commuters offered her a seat on eight subway lines while she was pregnant. She posted a series of pie charts with the results online earlier this month. The G train, which connects Brooklyn and Queens, was the worst; the 1 and 6, linking Manhattan and the Bronx, and the A, running through Manhattan, Brooklyn and Queens, were the best.
Some riders say the underground dining is just part of New York, where a dose of weirdness comes free with every $2.50 subway fare.
During a 15-minute ride on the 6 train this week, a passenger could see: a man descending a stairway while baaing like a sheep, a pair of old men belting out "Papa was a Rolling Stone" at triple its normal speed and a woman in a huge, fur-lined parka hissing at two large rats on a platform.
Until smartphones invaded New York, such sights could only be enjoyed by locals or in the Metropolitan Diary feature in Monday's New York Times, where readers send in anecdotes about the city. But now the oddness is online for all to see.
In recent months, amateur videographers have recorded a rat scampering up the leg of a sleeping passenger, a shoving match between a passenger and a belligerent saxophonist and a commuter train barreling along an elevated track in Harlem with one of its doors stuck open.
Some riders wondered if the spaghetti scuffle was staged. Most have seen much worse violators of etiquette than the noodle-nosher in the video, said subway rider Shash Lachhman.
"I once saw somebody eating barbecued chicken with no napkins," Lachhman said. "But I still don't think you need a rule against it."