"You can casually, again, walking down the hallway run into a reporter and make a remark that can set off World War III or tank the stock market."
"At least the expectations aren't that great," Gibbs joked.
Is he ready?
"I'm in the process of getting ready for it," he said. "I don't think I'd be here if people didn't have confidence in my ability to do this."
Can he watch his tongue?
"I think I can," Gibbs said. "I am sure there will be many that will test that premise. I sure there will be people who will keep this tape and play it back when I don't. But again, I look at this as a tremendous honor, what the president-elect has given to me. And I understand -- I think I understand what's at stake, and I understand that this isn't about me, that it's about something far bigger than that."
Perino also advised Gibbs that the toughest job is not defending "the president to the press. But an even tougher job sometimes is defending the press to the president, and speaking up for the press and making sure that they have access and get the answers that they need."
Gibbs insisted that the president-elect respects the job of the media, though he acknowledged there were times he thought reporters too focused on silly items.
"We were watching hundreds of thousands of people lose their jobs, and we were debating the meaning of the phrase 'lipstick on a pig,'" Gibbs recalled. "But let me use another sort of colloquialism. Hopefully this won't be maligned quite as much as that one is. But I think what Dana says there is, 'You get more flies than you do with vinegar.'"
McClellan, who famously complained about being misled by former senior Bush aides Lewis "Scooter" Libby and Karl Rove during the investigation into the leak of Valerie Plames' identity as a CIA operative, advised Gibbs: "You want to be able to vouch for yourself and for the president, but be careful about vouching for others.
"When you're not in that room when someone was maybe involved in something, you need to be very careful about trying to speak for them," McClellan said. "Let that person either speak for him or herself or make sure you carefully couch how you phrase something, saying that those individuals assured me that they were doing such and such or not doing such and such.
"You want to be very careful about that because when you're not there someone may tell you one thing but you can't know with absolute certainty and so you want to be careful about who you vouch for beyond yourself and the president."
But Gibbs seemed unworried.
"I believe that the people ... the president-elect has been able to assemble in a government that will take over on the 20th of January, I think we've put together a caliber of people that not only that I trust, but certainly have the trust of the president-elect, and I think that's extremely important," he said.
But isn't it inherent in what President-elect Obama has done with his Cabinet – selecting so many strong personalities in his "Team of Rivals," including four former primary opponents – that one will maybe occasionally wander off the reservation?
"I think the far greater risk is assembling a group of people that whenever the president opens their mouth they all nod their heads in agreement," Gibbs said. The president-elect "wants and expects there to be disagreement within that room."
But "there is one person in that room that is going to make the ultimate and final decision. That's going to be President-elect Barack Obama," he said. "And despite the arguments that you may have in the room about the direction or the decisions that you make on different issues, he expects each and every one of us to get behind the decision that's ultimately made, because he is the president of the United States."
ABC News' Mary Bruce and Kirit Radia contributed to this report.