So as he got up to get a sandwich, unknown to him, his whole life had changed. From the time he walked from his computer to the kitchen and back, Thomson had been selected by the A's in the 12th round of the 2010 First-Year Player Draft.
But it's not like Thomson hadn't heard his name called before. In fact, Thomson was drafted in 2007 (22nd round by Toronto) and in 2009 (12th round by Detroit).
"I'm a lot more excited, because this time I know it's going to happen," Thomson said. "There's no maybes this time, or going backwards or going back to school. This is it."
Meanwhile, A.J. Griffin, Thomson's three-year teammate at the University of San Diego, was relaxing in Pacific Beach, Calif., waiting to hear his name called.
Funny thing, the A's drafted Griffin with their 13th-round pick, less than a half hour after they selected Thomson. Oakland should have no problems signing the two right-handed pitchers before the Aug. 16 deadline, as both just wrapped up their senior seasons.
"It's pretty neat, man," Griffin said. "It's like they had it all planned out or something. It's a pretty cool coincidence."
It was a banner day for the USD baseball program, as eight Toreros were selected on Tuesday. The group includes five pitchers, including lefty Sammy Solis, taken by Washington to start the second round, and righty Kyle Blair, who was drafted by Cleveland in the fourth round.
Thomson and Griffin pitched with current Baltimore Orioles starter Brian Matusz on the '08 USD staff.
"It's friendly competition," Griffin said of playing at USD. "We all push each other to rise up to the occasion and just get the job done. It's a good experience and it's good to have that type of group around."
Griffin was drafted by the Philadelphia Phillies last season in the 34th round, partly due to financial reasons. Griffin said he was looking for more money than teams wanted to offer, so he slipped down draft boards before deciding to return to USD for his senior season.
Griffin said he had little idea that the A's were interested in his services, and that he barely talked to the Oakland organization.
"Griffin is a proven college performer," said A's director of scouting Eric Kubota.
Thomson, meanwhile, had been on the Oakland radar since 2007, when he played at Santa Rosa (Calif.) Junior College, about an hour north of the Oakland Coliseum.
"We've seen a lot of him," Kubota said. "We've seen him in junior college, at USD and in the Cape Cod League. He's got a strong arm with a good slider."
A Santa Rosa native, Thomson said he's been a fan of both the A's and the Giants growing up. He said he used to love going to Oakland games on Wednesdays, when tickets and hot dogs were only a dollar each.
Both Thomson and Griffin alike said they were excited to join an organization that has done a good job of developing young pitchers. Currently, the A's have the youngest pitching staff in the Majors, with an average age of 26.6 years.
"Over the years -- just from being in the Bay Area -- I know all the great pitchers that have come through the organization," Thomson said. "I want to go out there as soon as I can and start pitching."
Alex Espinoza is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.