The interns cram for their boards as Burke tries to get a disinterested Cristina to sample cakes for the wedding. As far as the medical cases are concerned, we have two words for you: Penis Fish.
The chairman of the hospital board, Larry Jennings, is admitted. His testicles have become horribly swollen after returning from an exotic trip with his assistant/mistress, Celeste. X-rays reveal that a rare fish swam up his penis while he peed in the Amazon River. It’s a lesson for all you kids out there…always go potty before leaving the house! Now the fish is lodged in Jennings’ bladder and they must operate immediately.
A man who's had a runny nose for weeks comes into the clinic for the fourth time. Thinking it’s nothing more than a cold, Bailey wants to send the man home. But when she sees blood on his pillow, she orders a CT scan. It turns out he was leaking spinal fluid through his nose because of a brain herniation. Bailey feels terrible about having sent him home three times before and insists on scrubbing in.
Ava, aka Jane Doe, is on bed rest near the nurses’ station, which means she gets all the good gossip. She hears about Addison’s “no sex” bet with Sloan and spills the news to Alex. When Ava starts seizing, they need to do an emergency C-section. Ava panics but Alex assures her she's ready and she's not alone.
Addison confronts Alex in the hallway, demanding to know if she has another Denny Duquette situation on her hands. In the heat of their confrontation, she kisses him and pushes him into the nearest room where they tear each other's clothes off. Mark sees them emerge from the room afterward and puts two and two together.
Callie confides to Addison that she knows George was with Izzie even though he said he wasn't. She's sure it's nothing but Addison tells her that her instincts are probably right. At lunch, Meredith says the “penis fish” is "instant karma" for cheating. Everyone leaves the table but George and Izzie, who say feel that even though they slept together, they’re just friends, so everything is fine. Callie catches them playfully feeding each other cake and walks away in disgust. Maybe she just doesn’t like cake. Then again, maybe not.
Cristina tries to get Callie's “legendary” intern exam study flashcards but Callie says no. But when Cristina gripes that she's just going to give them to George, who'll only share them with Izzie since they're "like an exclusive little unit," Callie hands the cards over. Callie corners Izzie saying she can't compete with her, since Izzie is George's best friend. She begs, "Give me my husband back.” It’s both heartfelt and panicked.
Richard removes the penis fish from Jennings. He also tells Bailey to stop beating herself up about the one case she got wrong. George tries to chat with Izzie but she tells him he's her penis fish. He's latched on and she can't get rid of him, so things are not okay. Meanwhile, Jennings’ wife tells George, "The wife always knows."
Izzie is sadly eating wedding cake samples when Burke asks which one she likes best. He says no one ever tells him anything, so she tells him she slept with George. Burke tries to steer the chat back to cakes by saying how much his wedding day and Cristina mean to him. Cristina is busy studying with Callie's notes when Burke asks which cake she likes best. She finally picks the same one Izzie did. Preston seems pleased. The cake was red velvet, by the way. Yum!
Meredith goes to see Derek at his trailer. He tells her he can't get over the fact that when she fell in the water during the ferry tragedy, she didn't swim. Ever since then, he's been trying to breathe for her, he says and he doesn't know if he can keep doing that. She says she should go and Derek doesn't stop her.
Addison asks Mark out for a drink so they can talk, but he lies and says he slept with someone, so the bet is off. We’re actually kinda moved by how hurt McSteamy is now that he realizes he and Addison will never be together. Later, Addison finds Alex studying and volunteers to quiz him. He tells her she's not his girlfriend and that he's busy. Now we feel bad for Addison. Grey’s can be such a roller coaster ride sometimes.