This scene is so cute :)

Richard: I hear congratulations are in order
Meredith: What?
Richard: The engagement. Our very own Seattle Grace wedding. I couldn't be happier for the both of you.
Meredith: Thank you Sir. Did you have an assignment for me?
Richard: Dresses.
Meredith: I'm sorry?
Richard: Stevens has transformed her room into a bridal boutique. So go, try on dresses. That's an order.
Derek: I didn't think you wanted to wear a wedding dress?
Meredith: I don't! How does he even know we're engaged?
Derek: Richard's my friend. He's not the one that ordered the dress. If you don't wanna wear a wedding dress, talk to Izzie.
Meredith: Oh yeah! As the chemo drips into her cancery arm. And she looks at me with those cancery eyes. Those cancery wedding loving eyes!
Derek: Be strong.
Meredith: We will have brides maids in pink taffeta! And you will be wearing a top hat and a morning coat! And somebody will be singing wind beneath my fricking wings!
Derek: You want me to talk to her?
(Der talks to Izzie, Mer waits outside. Izzie is crying)
Izzie: Okay, I'm really glad we talked.
(Der leaves her room)
Derek: Apparently a morning coat is non-negotiable. Also, we have to make time for ballroom dancing lessons.
(Mer looks at Der, totally freaked. Der walks away dumbfounded)