Sheldon and Wil Wheaton finally end their feud.
The title refers to Bernadette's reaction to Howard's news that he will be going into space in a Russian rocket.
Penny: Wait, what is going on?
Sheldon: In case you have forgotten, Schrodinger's cat is a thought experiment...
Penny: No no, I didn't forget. Umm, there's this cat in a box, and until you open it, it's either dead or alive or both. Although back in Nebraska, our cat got stuck in my brother's camp trunk and we did not need to open it to know there was all kinds of dead cat in there.
Amy: Homespun stories, knowledge of physics, and a bosom that defies it, you're the whole package, aren't you?
Bernadette: Are those Russian rockets safe?
Howard: Well, as safe as it can be when it was built by the good folks who brought you Chernobyl.
Amy: I don't understand, what difference does it make if Leonard goes to Wil Wheaton's party?
Penny: Wil Wheaton is Sheldon's mortal enemy.
Amy: Sheldon I know you are a bit of a left handed monkey wrench but, you really have a mortal enemy?
Sheldon: In fact I have 61 of them. Would you like to see the list?
Penny: Oh, say no, say no, say no, say no...
Sheldon: You just got off the list, would you like back on it?