Howard gets a new car but is assigned a parking spot that was formerly assigned to Dr. Sheldon Cooper. Despite the fact that Sheldon doesn't own a car (or even know how to drive), he feels strongly territorial about this parking spot, triggering a war with Howard. Among other stages in this conflict, Sheldon steals Howard's Iron Man helmet, Howard sits naked in Sheldon's spot on the couch, and Sheldon returns the favor in Howard's car.
Unfortunately, the rivalry between them on this score spills over between Amy and Bernadette, and Penny is caught in the crossfire.
Plus, there's a fun (but unscientific) running gag where Raj is obsessed with the idea that mummies and zombies are the same thing. (Note: They're not.)
This Episode's Science
Theoretical Physics - A major theme of this episode is the debate over Howard's achievements as an astronaut and Sheldon's work as a theoretical physicist. Bernadette rightly points out that Sheldon's work, which primarily consists of work related to string theory, has not been experimentally confirmed. Despite this, however, such theoretical work rightfully draws a great deal of academic respect within the physics community.
Quantum Gravity - In an attempt to make it clear that he's more significant than Howard, Sheldon begins listing his academic accomplishments in the field of theoretical physics related to quantum gravity.
Bose-Einstein Condensate - Among his accolades, Sheldon lists his work in furthering the theoretical understanding of Bose-Einstein condensates, a form of matter that manifests when bosons are reduced to very low temperatures, typically near absolute zero. For example, when helium gas is reduced to temperatures in this range, it transforms into the exotic state of matter known as a superfluid.
Lipid Residue - At the end of the episode, Sheldon takes his cushion to the laundromat to clean it. He is concerned about Howard's diet and wants tests performed for "lipid residue" or other biological remnants from the experience.
Bernadette: I'm really sorry they took Sheldon's spot away. He shouldn't have to suffer just because Howard's such a big deal now.
Amy: You're right. Sheldon should just let Howard have his little moment in the sun.
Bernadette: What's that supposed to mean?
Amy: Well, Howard's never going to go to space again, but Sheldon will always be a genius.
Bernadette: You're right. And I'm sure Sheldon will get a parking spot again if and when he makes a worthwhile contribution to science.
Amy: If and when?...
Bernadette: ... None of Sheldon's theories have ever been definitively proven. My husband actually went into outer space.
Amy: And that's an impressive accomplishment. He's now an inspiration to millions of Americans who know you don't have to be special or even qualified to go into space.
Howard: It's not just a parking spot. He can't handle the fact that I'm a bigger deal than he is now.
Sheldon: Oh, preposterous! I have been solely responsible for this university's six new quantum gravity calculations, have changed the way we think about Bose-Einstein condensates, and I am also the one who got Nutter Butters in the cafeteria vending machine. Maybe you missed that news when you were floating around like a goof in outer space.
Laundromat Attendant: How can I help you?
Sheldon: According to information I gleaned from Yelp, you had great success when a SantoriaSuzie37 brought you a pair of leather slacks stained with chicken blood. I believe I may have a similar problem. [Up-ends a bag, dumping his couch cushion onto the laundromat counter.] This cushion experienced a nude revenge wiggle.
Laundromat Attendant: A what?
Sheldon: A naked man sat on it. Now, here's my concern. His diet is rich in fatty deli meats. What test do you have to detect lipid residue?
Laundromat Attendant: Lipid what?
Sheldon: Lipid residue. An anal autograph. A colon calling card, if you will.
Laundromat Attendant: Tuesday okay?
Sheldon: No, don't rush it. We may be dealing with befoulment on a molecular level.