She and Burke have a talk in the stairwell as she paces. Burke's not fazed at all and has the gall to tell her that Hahn doing the surgery is "a good thing if it means you'll stop obsessing." Way to treat the girlfriend who is worried about your professional career and reputation. Cristina is adamant that George must have told Richard why he wanted Hahn to replace Burke, and adds that he could even be considering her as the next head of cardiothoracic surgery. This apparently triggers her memory, and only now does she pass along the message that the Chief wants to speak to him. She again talks about lining up their stories, but he high-horses it and says it's not him to do that kind of thing. It's his "kind of thing" to not fess up to a physical ailment and to conduct surgery when he's absolutely not fit, but lying is out of the question? Sure, I get that. He says he'll tell the truth, and storms out before she can stop him.
In the O'Malley room, Izzie asks them why they chose to change surgeons. She's really respectful about it, just curious and maybe confused. They both tell her that George made the decision, and muse that maybe he fell out with Burke. Mrs. O'Malley then excitedly wonders if he's going out with Dr. Hahn. I have officially never seen a mother so intent that her son get laid. Mr. O'Malley reiterates that Callie is in love with George, which leads Mrs. O to ask why she would break up with him if she loved him. She asks Izzie in a conspiratorial girl-talk way, which is maybe what leads to the horror that comes next. Izzie asks what she knows, and Mrs. O'Malley assures her that it's everything, because she is his mom. Taking this at face value, Izzie launches into Callie being "out there" and how much she's naked. Both the 'rents are understandably shocked, which Izzie notices, and softens. She points out that "George seemed to really like her, and he kind of needed her." I'm proud of her for saying that, even if admitting those things came in the middle of this car wreck of a conversation. Because he especially needed her after the "Meredith thing... " which of course they also knew nothing about. The one great moment in all of this embarrassment is how proud Mr. O'Malley is that his sons are studs. The least Izzie can do to make things right is assure them that there's nothing going on with George and Dr. Hahn, and so they again ask why she'd be doing the surgery if she's not better than Burke. Izzie concedes that she's good, but Burke is the best, so they put Izzie on the case to find out why he's not going to be their surgeon.