The pub's owners had the stout poured as about 400 people crowded into the restaurant and onto the patio to watch as the cup filled.
The glass alone weighs 900 pounds, Auld Dubliner co-owner David Copley said. The stout alone weighs 2,772 pounds, said co-owner Eric Johnson after the full glass had been weighed.
"It's incredible. It was worth being a part of," said Tustin resident Randy Barnes, who was at the Auld Dubliner with friend Todd Fisher.
The glass will be on display for the next three months, but Johnson said they're planning to drink the stout by 2 a.m. Sunday.
"We dipped our glasses in, and we have a pump," Johnson said. "We're going to drink it."
The glass will then tour the other Auld Dubliners, in Orange, Long Beach, Riverside, Olympic Valley and Mammoth Lakes, Peoria and Tuscon, Ariz., Henderson, Nev., and Bolingbrook, Ill.
Copley said the idea came about while watching an award given for making the world's largest Irish coffee. He and Johnson decided they'd do the largest Guinness pour, he said.
"Guinness seemed the obvious choice. We're an Irish pub and Guinness is synonymous with Ireland," Copley said.
Shannon Rozar, of Orange, said she came to the event because she's Irish and enjoys drinking Guinness.
"We're major Guinness fans," said David Anton of Orange. "It seemed like a good way to pass the afternoon."
The cup, made by Ontario-based California Quality Plastics, was acrylic so it wouldn't break. The band Craic House performed as the audience watched Guinness pour from two spouts.
The restaurant sold T-shirts and glasses of Guinness to commemorate the moment. The proceeds benefit the Orange County Fallen Fireman's Fund.
The Auld Dubliner is trying the break the record set in February 2008 by Harry Caray's Italian Steakhouse in Chicago. Harry Caray's created a 4-foot-tall, hexagonal, 100-gallon glass with a handle and spigot for serving. That glass weighed about 1,000 pounds when filled.
The largest tankard of beer, according to the Guinness World Records Web site, was filled in Poznan, Poland, in March 2007. The bronze tankard was 17-feet, 8-inches tall and was filled with 1,760 gallons of Lech.