Webber, Mark and others in “What A Difference A Day Makes”

Webber

We'll be out of here in plenty of time for the wedding.

Mark

Good. Then she won't have any excuses.

Meredith

Excuse me?

Mark

This is the second time I've been Derek's best man. I have to come up with a toast, offer some words of wisdom. It's a lot of work. I don't want to have to be his best man a third time if you know what I mean.

Meredith

So you came in here to threaten me?

Mark

I'm his best man. That's my job.