7th Episode Twist: In "The Mall", Kent is hit by a car and he (informally) begins a relationship with Holly. It becomes formal in the very next episode, "The Sin."
Above the Influence: Jimmy subverts the trope when he takes advantage of a drunk Samara on the anniversary of her late sister's birthday in "The Performance."
Absolute Cleavage: When the gang is at a Coolest Club Ever in "The Renewal," this is why Jimmy suggests it will be easy to find their classmate Stacey Milano. He tries using his hands to demonstrate their size, but this doesn't go so well.
Beta Couple: Claire/Jimmy serve as a negative foil for Kent/Holly in the first season.
Beauty, Brains and Brawn: Lex, Melanie and Terra are the beauty, brawn and brains of Holly's friends from dance class.
The Bet: Milo bets Tom he can deflower the latter's cousin Carrie when she visits for an episode. Tom, who wouldn't ordinarily tolerate such an act, goes through with the bet because he knows his cousin - and he wins. And he gives Carrie the money.
Better as Friends: Rusty went out on one date each with Holly and Claire in middle school, and that was the end of that. At least for a little while.
Big Applesauce: Samara's family is from the Big Apple, and she moves on to NYU after graduation.
Big Fancy House: Surprisingly averted with Kent and his family.
Blackmail: Jimmy's usage of this (a Scarpia Ultimatum) on Claire and indirectly Kent in "The Twist," is arguably the turning point of the entire storyline.
The Bro Code: Mike supposedly violates this for dating Iris after her breakup with Rick, but it is Rick himself who really breaks the rules by sleeping with Mike's ex Cassie and taunting Mike with the video of it.
Brooding Boy, Gentle Girl: While Kent isn't unhappy to the point of constant brooding thanks to good friends like Tom, Holly nevertheless expands his horizons and generally makes him feel better about himself.
But Liquor Is Quicker: Stacey is mentioned as a frequent victim of this, and Jimmy uses this method to sleep with Samara on the anniversary of her late sister's birthday.
California University: Played realistically, with the gang separating to attend different universities across the state (or country) at series' end.
Can Not Spit It Out: In "The Noodles," when Kent first tries to tell Holly he likes her, it backfires...and he ends up telling her he likes Claireinstead. More severely, Claire's inability to tell Jimmy she loves him back is one the factors that helps drive him over the edge.
Catholic School Girls Rule: Invoked by Holly and Jessie in the second Halloween episode, both of them vying for Kent's attention.
Jimmy: "...unlike you, I'm not ashamed of anything. If my parents were to catch me in my room right now with my pants down, listening to you, I'd tell 'em to fuck off."
Celeb Crush: Several characters have the benign type: Kent likes Alexis Bledel, Holly likes Eric Bana, and Claire likes Johnny Depp and Adam Brody.
Character Filibuster: Samara is prone to doing this almost Once an Episode, much to the annoyance of everyone else, but other characters, particularly Claire and Kent, will engage in a sizable speech if someone pushes their buttons enough.
Club Stub: In "The Club," Kent's attempt at creating an on-campus nature club fails spectacularly when no one shows up but himself - and later, Claire, who's trying to hook him up with Holly for the Homecoming Dance. Ultimately, the club shuts down after one meeting, and Holly ends up going to the dance alone.
Holly: "You know what? You should make sure not to look for me sometime! Then you can not add me as a friend and we can not see each other every time we don't log on!"
Cool Car: Kent receives a Porsche for his 16th birthday from his parents, and although he accepts it, he ultimately plans on replacing it with something more suited to his lifestyle.
Country Matters: Beginning in "The Switch," when Rod first calls Claire this for her overreaction to Kent's kissing of Holly (despite having not met either of the girls yet), the word is tossed around more frequently than it should, mostly in reference to this incident.
A Date with Rosie Palms: Alluded to many times by these Genre Savvy teenagers. Most notably, in "The Distance," an increasingly frustrated Holly leaves an embarrassing message on Kent's relatives' machine. Such are the perils of Kent not having a cell phone.
Diamonds in the Buff: Holly takes a picture of herself in the tub wearing only Kent's birthday gift for her (a turquoise necklace) in "The Distance." This doesn't become important until much, much later.
Melanie: I think I might be a lesbian. (everyone does a double take, and the girls sitting next to her scoot to the side) I just said that out loud, didn't I?
Disproportionate Retribution: In "The Sin," when Kent pulls Holly in for their First Kiss, Claire immediately calls him a rapist and inadvertently (via Rowan) ends up getting him sent to the office. The misunderstanding is cleared up, but not before Rod finds out and the trope is taken even further.
Rick joins this camp when he sleeps with Cassie and sends the video of it to her ex-boyfriend Mike in response to Mike beginning to date Rick's ex Iris.
Distracted by the Sexy: Rusty and Claire both have moments of this in "The Distance," when they both spend the day with each other in their underwear to get back at Jimmy.
Double Entendre: Besides being a common feature of the dialogue, this is also seen in many episode titles (e.g., "The Treasure" refers both to the episode's theme and to the movie the gang sees in it).
Drama Class: Holly, Claire, Rusty, Tom, and Samara are all in this class at school from the beginning; Kent and certain others join them in the later seasons.
Drugs Are Bad: Averted with Rusty (a sympathetic drug dealer who provides marijuana to his friends), played straight with Jimmy, who begins taking harder drugs with his descent into villainy.
Evil Gloating: Jimmy brags about cheating on Claire right after she finally tells him she loves him in "The Charm."
False Start: How Kent and Holly's relationship begins.
Fangirl: Several, primarily Mila (Twilight), Emily (Justin Bieber, KidComs) and Dana (Star Wars). However, only Emily's fandom could be considered shallow, with Mila scoffing at the more obsessed Twilight fans and Dana having inherited a deep-rooted family love of Star Wars.
First Name Basis: The high school drama teachers, Roger and Diane Bowman, get this from their students due to the laid-back Nakama nature of their class.
First Kiss: Kent and Holly share this in "The Sin".
The Glorious War of Sisterly Rivalry: Sloane and Nicole: they start out on a more or less even plane, but due to Jimmy's influences Sloane falls down the social ladder hard and fast, while Nicole remains unscathed.
Hormone-Addled Teenager: In "The Stickers," Kent, Holly, Claire and Rusty make a pact to stop talking about sex until one of them actually loses their virginity, in an attempt to subvert the trope. It goes about as well as you'd expect.
Instant Humiliation: Just Add YouTube!: In "The Noodles," Rusty records himself and Samara watching 2Girls1Cup and posts it online. Hilarity Ensues. Later, in "The Cross," ex-boyfriend Cameron wants to get back at her in a similar way, by hijacking the school news feed. Jimmy has other plans.
I Uh You Too: When Jimmy tells Claire he loves her, her decision to not tell him the same until she feels it is one of many things that helps to drive them apart. When Holly tells Kent she loves him over the phone while he's in New Jersey, he chooses not to respond until he gets back to California.
Joisey: Kent's parents are originally from here, and that's where the rest of his family lives, including his godparents, Aunt Theresa and Uncle Calvin, who specifically reside in Pemberton, part of the Philadelphia metro area.
Tom: "...I know this is our lives and not some TV writer's script, but does anyone else think the whole 'Person A cheating on Person B' storyline is starting to get ridiculous here?"
Lets Wait Awhile: Kent and Holly are this way while dating, and so are Claire and Jimmy, although as part of his growing antagonism towards Kent, Jimmy becomes less patient as time goes by, enough to invoke a Scarpia Ultimatum to get Claire to finally sleep with him.
Living Lie Detector: Samara shows traits of one. Most notably, when Jimmy makes a Suspiciously Specific Denial of any infidelity in "The Renewal," she changes his nickname from "Time Bomb" to "The Big Bang."
Long Distance Relationship: Tom and Oriel, who live an hour apart in La Crescenta and Long Beach, respectively. Later, Melanie and Kristen, who live in the same respective places.
Los Angeles: Specifically, set in the Glendale area, at the eastern end of the San Fernando Valley.
Love Dodecahedron: Discussed in "The Renewal," before any cheating has even been revealed, as a result of Samara continually suggesting that this is what's going on.
Narrative Profanity Filter: In "The Treasure," we're told that Jimmy insults Claire's mother quite loudly when she won't give him a ride home with the other kids after the movie.
Rowan: (speaking into his cell phone) "No, Dad, that wasn't me."
Nice Guys Finish Last: Kent invokes this trope as justification to not bother talking to Holly when she appears on the bus with him and Tom in "The Mall". Luckily, Tom convinces him otherwise.
One Steve Limit: Averted. There are two people named some variation of Sam, but one (Samara) is a student and main character, while the other (Sam Greene) is an adult and only occasional supporting character. In addition, there are also two minor supporting characters named Nicole: the first, Nicole Sullivan, is a classmate of the main cast members, while the second, Nicole Rivers, is the older sister of another classmate, Sloane.
Ostentatious Secret: In the beginning, Kent openly admits to Holly and the others (except Tom) that he's hiding something from them, and will tell them when he's ready. Then Claire finds out what it is in "The Twist," he only allows her to tell one person, and she picks the wrong one. Kent finally opens up after that to avoid further misfortune for anyone else.
The Other Rainforest: Dana is a wildlife student at Humboldt State University, among the redwoods in northern California, and her influence is what ultimately persuades Kent to go there for his college education.
Kent: (after being asked for his opinion on National Treasure 2) "I for one think there are much better Jerry Bruckheimer-produced movies starring Nicolas Cage and Ed Harris out there. Those movies are called The Rock."
Scarpia Ultimatum: Done by Jimmy to Claire in "The Twist," when she reveals to him the then-secret of Kent's wealth and he threatens to tell everyone or else. They both end up losing their virginity.
School Play: As most of the cast are in or eventually join the high school drama classes, this is inevitable.
Rusty: "You're not wrong, Jimmy, you're just an asshole."
Claire: "I know you're both shamelessly competing for my affections, but I sure appreciate that you can work together to make Big Lebowski references when you argue."
Show Within a Show: In addition to the several student plays, there's also The Swanson Princess, a fictional Disney Channel show watched fervently by Emily.
Sibling Triangle: Scott ends up in a brief one between his girlfriend, Sloane, and her older sister, Nicole, after they engage in Three-Way Sex per Jimmy's suggestion. Besides the Squick factor both sisters admit to, it becomes worse when Jimmy's plan to sleep with a disgruntled Sloane afterward comes to fruition.
Status Quo Is God: Lampshaded by Kent at the beginning of the third season.
Sweet Home Alabama: Mike spent his earliest years in Huntsville before his family moved to California; Cassie was much the same, except she came from Memphis, Tennessee.
Thanksgiving Episode: Holly and Kent meet each others' families and Claire opens up to her own about her flawed relationship with Jimmy in "The Parents," set on this holiday.
Their First Time: Jimmy and Claire consummate their relationship in "The Twist," with bad results. Kent and Holly attempt to lose their virginity in "The Charm," but the consequences of Jimmy's revelations earlier prevent them from thinking clearly and they are unable to continue.
There Is No Kill Like Overkill: Invoked in "The Renewal," when Jimmy and Cameron are discussing solutions to the latter's frustration with ex-girlfriend Samara:
Thirteen Is Unlucky: In "The Birthday," Tom remarks on the fact that Kent (December 14) and Holly's (December 27) births are separated by only thirteen days.
Three Amigos: Holly, Claire and Rusty; Rick, Mike and Iris.
A Threesome is Hot: Subverted. We don't see it, but when Jimmy suggests this to Scott as a solution to his problem, it ends up ruining Scott's relationship with Sloane (although it does fix the original problem). Of course, this was the plan from the start, enabling Jimmy to sleep with Sloane in the aftermath. After they break up, Samara invokes the idea that we're supposed to feel sorry for him about this.
Very Punchable Man: Andrew in "The Renewal," who exists solely to have sex with Stacey before getting punched out by John. Until he returns in a few later episodes.
Jimmy: "Sweet, I get to punch somebody." (except he doesn't)
Wham Episode: "The Charm," the mid-season finale of Autumn, in which, after Claire finally tells Jimmy she loves him, he immediately rejects her and gloats about his affairs with three other girls, two of whom are at the dance that night with other dates. Shortly afterward, Jimmy begins his secret collaboration with Rod.
Your Cheating Heart: Jimmy cheats on Claire (three times) after becoming suspicious of her relationship with Kent. Through backstory, we learn that Holly's mother Pam cheated on her father Mark; Claire's father Walter cheated on her mother Lisa; and Kent's (still-together) parents are both notorious cheaters to this day.
Barely subverted with Rick when he and Iris break up before he has the chance to cheat on her with Mila. Played straight again some time later when Mike is seduced by Kristen while in a relationship with Iris. Later still, Rick sleeps with Sloane (and possibly puts a bun in her oven) when she turns to him to escape from Jimmy's corrupt ways. Yeah, this trope is awfully prevalent in the series.