While playing Sheldon's theoretical physics board game, Penny tells the guys that her ex-boyfriend Justin, a guitarist, is coming for a visit. This sparks a fight, upsetting Sheldon. He at first orders Penny and Leonard to apologize to each other but both are too arrogant and self-righteous about their own behavior to do so. At the Cheesecake Factory, Sheldon tells Penny that Leonard is bothered by a lot of faults with her such as her stuffed animals and her neglectful, reckless driving. When this doesn't work, Sheldon tries hiding out at Raj's or Howard's but they're having arguments with their parents, scaring away Sheldon once again. As Penny and Leonard are about to reignite their fighting in the apartment room, Penny takes more concern in Sheldon disappearing during nighttime when it's dark and Sheldon doesn't even have his own car so she starts searching for him throughout the city. Leonard tags along to reprove that her driving skills are abhorrently abysmal and insure their argument doesn't go unresolved.
Leonard and Penny find Sheldon hiding in the comic book store, and Penny shoots down Stuart's obnoxious flirting and attempt to win her back. After finding Sheldon, Leonard and Penny go back to arguing in the store about Justin's sleeping in Penny's apartment, but Sheldon (rudely) interferes again with loud noises this time from toy robots. Exhausted both emotionally and physically, Penny agrees not to let Justin sleep in her room anymore and kicks him out to make amends with Leonard, as the two are now sleeping together happily agreeing to put the whole day behind them. We then see that Sheldon agreed to take in Justin, who is fast asleep on the couch save for Sheldon's spot.
- Artistic License Law: Penny somehow doesn't get pulled over by the police for running several stop signs.
- Double Standard: Sheldon calls Penny out on this. Leonard overlooks most of the things that annoy him about her, but she doesn't allow Leonard's faults to slide so easily.
- Formerly Fat: Lakshmi, the girl Raj's parents are trying to set him up with; also a Call-Forward to when we see her later.
- Girls Love Stuffed Animals: One of Leonard's list of grievances include the stuffed animals on Penny's bed staring at him.
- Halfway Plot Switch: At first, the episode looks like it's going to be focusing on whether Penny's an inconsiderate girlfriend, or Leonard is an overly-controlling boyfriend. Over the course of the episode, however, the story switches to focusing primarily on Sheldon and the neuroses from his troubled childhood, with the conflict between Leonard and Penny being resolved off-screen.
- Happy Place: Leonard and Penny's fighting force Sheldon to retreat to the comic book store.
- It's All About Me: Sheldon's not at all concerned with his friends being unhappy. Though considering how he is very tense to people fighting, this could be considered moot.Penny: Well, Im sorry, Sheldon, but this really isnt about you.
Sheldon: I dont follow.
- Layman's Terms: When Penny and Leonard find Sheldon in the comic book store.Leonard: He does this thing where he pretends he's in an alternate dimension that occupies the same physical space we're in but he can't perceive us.
Sheldon: Don't flatter yourself. I'm just ignoring you.
- Mama's Boy: Raj calls Howard one. Howard skipped taking a couples cooking class in favor of a juice fast with his mother.
- Manchild: Sheldon has always been a bit of one, but it really shines here. Sheldon does not like arguing because it reminds him too much of how his parents acted in his childhood. Thus he tries to drown out Leonard and Penny's arguing and tries to get one of them to apologize just to be done with it. When they don't stop and he sees that his others friends are having their own arguments he wants no part in, resorts to childish things like running away and ignoring everyone. When Leonard eventually tells him he needs to grow up and move on from his childhood pains, Sheldon responds by blaring an action figure in his face.
- Nice Job Breaking It, Hero!: While Sheldon tries to get Penny to apologize to Leonard, he ends up making it worse by bringing up Leonard's own grievances.Sheldon: Were you under the impression that Leonard has no complaints about you?
Penny: Like what? (To another customer) Yeah, yeah, I see you, you're making a little "check" sign in the air, I got it, just hold your horses. (Back to Sheldon) What does Leonard complain about?
Sheldon: Your driving, the plethora of stuffed animals on your bed that stare at him during your amorous activities, your constant tardiness, your singing.
Penny: My singing?
Sheldon: That's actually from my list, but Leonard would be a fool if he didnt agree with it.
Penny: Okay, if Leonard has so many problems with me, why hasn't he just said so?
Sheldon: Because, according to him, you're oversensitive and have a temper.
Penny: Oh, really? Well, then, do me a favor and tell Leonard that he can drop dead! (she leaves)
Sheldon: (To himself) And she wonders why she's constantly under-tipped.
- Screw This, I'm Outta Here!: Sheldon does this three times when he had to listen to people fighting. First, he begged Leonard to pull over so he wouldn't have to listen to Leonard complaining. Second was after he yelled at Howard and Raj over their skewed priorities, and finally, he leaves his apartment when Leonard and Penny fight for a third time, sending them after him and finding him at his happy place: the comic book store.
- Silent Treatment: Sheldon refuses to talk to Leonard or Penny at the comic book store.
- Trauma Button: Sheldon loses his composure four times when he is in the presence of two disputing people (though the first time, it was just Leonard arguing with himself). This is apparently due to being around fights involving his parents when he was a kid.