"I wouldn't say I'm great," a humble Cera, 22, told PEOPLE at San Diego's Comic-Con International, but he did admit his costars "didn't know what they were getting into … I play in a really good game in L.A. with really good players, people who are a few levels above me.
"I just try to walk away with my money from that game, and that's made me a better player."
There seemed to be no argument against that. "He's a damn good poker player, and he takes all your money," said Cera's costar Johnny Simmons. "Michael and Keiran Culkin are shark-level. I lost so much per diem to those guys."
The actors found themselves with so much free time on their hands because of the complicated action setups being staged by director Edgar Wright that Cera was frequently able to fatten his wallet – though not for long.
"We went to the casino a lot while making this movie, and I lost a lot of money there," he admitted. "Anything that I won in poker I lost at the casino."