Season 2, Episode 12: "Grandma Got Run Over by a Reindeer"
It's Grey's first Christmas episode! We have Izzie, who lives and breathes the holidays, and Cristina, who's a bit of a Grinch when it comes to getting festive. But for Cristina, the issue runs deeper, since she thought she could rely on Burke not to be spiritual or religious. The tension between them builds when their young patient refuses a heart transplant. Meanwhile, the gang helps Alex study for his board exams the second time, making up hilarious scenarios and trying not to hurt Izzie (since he just cheated on her with "syph nurse"). In typical Grey's fashion, we see drama, but there's a happy ending.