Credit: Randy Holmes/ABC Television Group © 2010 Disney Photo: Dr. Richard Webber and Dr

Some major surgeries are going down, and it seems like the whole hospital is all a-Twitter. (We had to make that joke. You understand.) But first, let's discuss the fallout of last episode's final bombshell...

Baby Makes Four: Arizona is hoppin' mad about Callie sleeping with Mark, but it's not a dealbreaker for her — she's still committed. Callie spends the entire episode on the exam table of a young (hot) OB/GYN whom hypochondriac Callie forces to rule out every single baby problem. (You know Addison would not abide.) Callie gives Mark an out, saying he could be a cool uncle; but Mark wants to be a devoted, doting daddy. Arizona eventually warms up to the idea of being the third parent, so much so that she actually starts moving Callie's stuff back in to their old apartment, declaring that they're together (or "tuh-gether," as she pronounces it). Things don't go so smoothly with Lexie, though. Mark tries to downplay the drama, but Lexie realizes that she's been de-prioritized again and storms out in a heck of a huff and doesn't even turn off the stove on which she was cooking a delightful feast for her McSteamy.

Trials of the Trial: Derek starts his Alzheimer's clinical trial, and Meredith is galled that Alex is the one he chose to help out. But the two patients he operates on in this episode are both delegated by the heartless computer to receive a placebo instead of the drug. Daniel Cobb is one of the patients, and his wife Allison has to stand idly by while he swoons over another dementia-afflicted patient. She begs Alex to make sure Daniel gets the drug, but Alex has no say in the matter. After Daniel's operation, Alex quits the trial and encourages Derek to recruit Meredith and her twisted-ness, and Derek does.

Bailey's Tweet-ment: Bailey's once again operating on pancreases, which seem to be her bread and butter these days. But this time, she has recruited her assisting surgeons to live-tweet the surgery so that other residents — about 3,000 of them, to be exact — can follow along and ask questions along the way. The Chief finds out, spends some time being adorably ignorant about social networking, and then learns to embrace the technology when a neighboring hospital saves a patient.

Cristina, Sweet and Sour: Cristina and Jackson, both trying to show how Chief-Residently they are, give the best freakin' bedside manner ever to Martha, a nervous, elderly quadruple bypass patient. But it's not totally an act for Christina; she's actually being sorta genuinely kind. Jackson majorly steps in it when he mentions her extended hiatus. She gets her comeuppance by crying crocodile tears so convincing that even Mer is concerned, sending Jackson a massive guilt-o-gram. If these two aren't headed towards a break room makeout session soon, we're confused, Shonda.

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