Penny accidentally shoots Sheldon's beloved sofa cushion with a paintball gun. He is deeply disturbed by this turn of events and is not happy with the cushion even once it has been dry cleanned. Meanwhile, Howard starts sex sleeping with Leslie Winkle. She uses her control over CalTech grant money to make him do things that she wants.
Leonard, Sheldon, Howard, and Raj are playing paintball and are losing badly, which Sheldon believes is due to Howard missing his physics department paintball strategy meeting. After everyone leaves Howard to die, Leslie Winkle shows up and, after discussing how they might die soon, they kiss and end up having coitus. While everybody's departmental budgets are getting cut, Howard is getting new equipment especially since Leslie is controlling the money and they are having a "friends with benefits" relationship.
Penny goes to Leonard for help on her computer after spending three hours shopping for shoes. Noticing the paintball gun, she picks it up and accidentally shoots Sheldon's cushion leaving it with a big green spot on Sheldon's Spot.
Leslie and Howard have finished having sex as his transient idiopathic arrhythmia was acting up. Howard's mother is asking for help with her zipper, so Howard tells her to not come in. Leslie shouts that he has company. After Howard lies that she is Jewish, Howard's mother tells them to have fun and use protection.
Leonard tries, and fails, to clean it. Penny asks what they were going to do, while Leonard says that she had eighteen months to become "we". Penny turns the cushion over and puts her own butt print in it. Leonard admires her butt impression. Sheldon comes in, sits down and looks worried that something is not right. He turns the cushion over, finds the stain and Leonard immediately blames Penny.
The cushion is sent to the dry cleaners; however, Sheldon doesn't trust him since he also makes keys. He hops all over the apartment not comfortable to sit in any spot including when Howard gives him Raj's seat cushion.
Meanwhile, Leslie and Howard are sleeping together, and she invites him to a trip to the Large Hadron Collider project in Geneva, Switzerland and wants him to escort her to a relative's wedding. Howard realizes that she is just controlling him for sex. Leslie denies that and says the he is also arm candy.
After the cushion is back from being dry-cleaned, Sheldon is still not happy with it, and refuses to sit in it. Leonard tries to take his mind off of it by confessing that Szechuan Palace has been closed for two years, and his cashew chicken comes from Golden Dragon in Szechuan Palace containers. In the end, Sheldon is still unhappy with the dry-cleaned cushion.
Finally Penny has joined their weekend paintball expedition. While they are huddled in a shed on the paint-ball range to go over their game strategy, Sheldon kills Penny because of her cushion incident. Penny responded by shooting Sheldon, but that was not allowed in the rules, because she was dead, so Leonard kills Sheldon who then breaks the rules and kills Leonard, prompting the others to "surrender, then (go to) Denny's".
- Guest starring:
- Teleplay: Bill Prady & Lee Aronsohn
- Story: Chuck Lorre
- "If Leslie and Howard stay together to form a relationship then this episode will have served a frippin' purpose." The TV Critic's Review
- IMDb user reviews.
- Title Reference: The title refers to Penny accidentally shooting Sheldon's cushion with a paintball gun.
- Chuck Lorre's vanity card
- This episode was watched by 10.94 million people with a rating of 3.9 (adults 18-49).
- Episode transcript 
|Sheldon wears his AV Club shirt, the purple shirt with the Philips/Stooble test pattern, and the Kablaam Computer shirt|
|Build a Scene Part III|
Green Lantern & Flash
By the front door
in the alcove
|City of Villians|
in the alcove
|The Flash #247|
The last issue of Volume 2
- Sheldon says, "If my life were expressed as a function on a four-dimensional Cartesian coordinate system, that spot at the moment I first sat on it would be " The Minkowski space time combines space and time in a single, four-dimensional manifold which is covered by atlas_(topology)#charts|coordinate charts Coordinate charts are used in the space-time manifold to represent the events. Usually, Cartesian coordinates are used, though curvilinear coordinates are also allowed. In the most general case, a number of overlapping coordinate charts is needed to cover the entire manifold. A frame_of_reference|reference frame is identified with a Cartesian coordinate chart with a physical observer placed at its origin.
- Sheldon says that he does not eat in his desk chair, and he does not work in his spot. In "The Cooper-Nowitzki Theorem" (S2E6), he does work in his spot.
- In "The Codpiece Topology" (S2E2), Leslie Winkle tells Leonard that she is "done with casual sex and fully committed to the traditional relationship paradigm"; however, in this episode she seems to have abandoned the idea as she is sleeping with Howard outside of a romantic relationship.
- As Sheldon is trying to get comfy on the couch, he's reading The Flash #247 (the December 2008 issue)
- Sheldon makes a reference to the Stargate SG-1 episode Brief Candle (where SG-1 encounter a Greek-based civilization) when he suggests to his teammates to make a tactical retreat.
- There is no dry-cleaner scene in the final cut of this episode, although promotional photos feature one.
- Penny: What difference does it make?
- Sheldon: What difference does it make?
- Leonard: Here we go.
- Sheldon: That is my spot. In an ever-changing world, it is a single point of consistency. If my life were expressed as a function in a four-dimensional Cartesian coordinate system, that spot, at the moment I first sat on it, would be [0,0,0,0].
- Leonard: Why don't you just eat in your desk chair?
- Sheldon: Why don't I just eat in my desk chair?
- Penny: Here we go.
- Sheldon: That is my desk chair. That is where I work. I don't eat in my desk chair, and I don't work in my spot -- I work in my desk chair and eat in my spot.
- Leonard: (to Penny, about Sheldon) Wackadoodle.
- Penny: What are we going to do?
- Leonard: We? No, no, no. You had your chance to be we for, like, a year and a half now. Right now, you are you, and you are screwed.
- (Sheldon shoots Penny with a paintball gun to get revenge for his cushion)
- Penny: What the hell?!
- Sheldon: That was for my cushion.
- Leonard: Sheldon, Penny was our only hope.
- Sheldon: I'm sorry, but revenge is a dish best served cold.
- Penny: Screw that. (shoots Sheldon back with a paintball gun)
- Sheldon: She can't shoot me. She's dead.
- Leonard: He's right. You can't. (shoots Sheldon with a paintball gun)
- Sheldon: Well, if we're going to descend it to anarchy. (shoots Leonard back with a paintball gun)
- Howard: Okay, see you.
- (Howard, Raj and Leslie prepares to leave the shed)
- Leonard: Where are you going?
- Leslie: Surrender, then Denny's.