Amy: I think I might have a little surprise that might help get things back on track.
Sheldon: Intriguing. Is "back on track" a hint that it has something to do with trains?
Sheldon: Because if it did have to do with trains, and you were gonna give-
Amy: It's not about trains!
Sheldon: Oh. Not even a cozy sleeper car on the Orient Express?
Amy: Stop talking about trains!
Sheldon: Who's killing the mood now?