Sheldon: Well if the ushers are so important to you, what if I propose a trade? You may pick that, and I will decide, say, first dance.
Amy: Great. Then the ushers will be my cousins dressed in frontier frock coats.
Sheldon: Oh. And the first dance will be that we won't have one.
Amy: All right. Then our second dance will be the first dance.
Sheldon: Unless we have no dance at all.