The man, who told police he thought the person he hit was a grown man, was watching "Titanic" in 3-D with his girlfriend and had asked the people sitting behind to quiet down and stop throwing popcorn, but they laughed at him, he said.
"I got so mad that it just happened," Yong Hyun Kim, 21, told police who arrested him the night of April 11 at the AMC Kent Station 14, in Kent,Wash., a south Seattle suburb.
The 10-year-old lost a tooth and had a bloody nose in the confrontation.
Mr. Kim spent a night in the Kent city jail and appeared April 12 in King County District Court and was released, said county prosecutor's spokesman Dan Donohoe.
Kim was charged May 16 with second-degree assault. If convicted, he could be sentenced to three to nine months in jail, Mr. Donohoe said Tuesday.
The Auburn man will be arraigned May 31 at the Regional Justice Center in Kent.
A phone number for Kim could not be found, and it's unclear whether he has a lawyer.
The boy, identified in the police report as KJJ, was at the theater with three friends. They met police in the lobby. They said they were watching the movie and talking when Kim told them to be quiet. They quieted down, but KJJ says when he whispered something, Kim jumped over the seat, threw an iced drink at them and punched KJJ in the face.
Kim said something to the effect of "You know what, I paid a lot of money to see this movie," the police report said.
Kim told police the boys' behavior was worse than talking. He says they were hitting him and his girlfriend with popcorn, running back and forth in the aisle and bumping him with their arms.
"At one point Yong stepped over the seats and confronted the subjects behind him," the police report says. "Yong said he was talking to the subjects when they started laughing at him. Yong said he became so angry and swung his arm at one of the subjects and hit him in the face."
A manager at the theater referred a request for comment to a corporate spokesman.
"We strongly encourage guests to be respectful of their fellow moviegoers, and to report any disturbance to an AMC associate, so that we may handle it directly," AMC Theatres spokesman Ryan Noonan said in a statement. "The safety and security of our guests and associates is important to us, and we want everyone to enjoy the moviegoing experience."
Mr. Noonan said the theater's management told him no one had complained about audience behavior prior to the incident.