(Penny and Amy are going through wedding magazines)

Amy Farrah Fowler: It's just so hard to tell what will look good on me.

Penny Hofstadter: No. This is just to give you ideas. You know, do-do you want something simple and elegant? I mean, do you want a train?

Sheldon Cooper: Ooh, we're talking about trains.

Amy Farrah Fowler: Not the kind of trains you like.

Sheldon Cooper: Oh, I like all kinds of trains... steam, diesel, coal, elevated, bullet. I defy you to name a train that I don't like.

Penny Hofstadter: The kind on the back of a wedding dress?

Sheldon Cooper: I did not see that coming. Good job.