These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Alternative Character Interpretation: Although Carli is hated by many fans, Emily Head, who plays her disagrees that she is a bitch saying she gets exasperated around Simon because he "is such an idiot around her. She never sees the sweet, lovelorn side of him."
A reasonable interpretation may be that she is Drunk with Power around Simon only. She knows she has complete power over him and can make him do anything she wants because his love has made him blind, and she can't help taking advantage of this power. Around Will, Jay, Neil and other characters she seems fairly friendly or at least tolerable. She evens stopsDonovan when he gives Will a wedgie in The Movie.
Will's dad. At the start of the movie, he is played up as a Jerkass just like Jay's dad. But at the end of the movie, when Will sends him a text with a picture of himself and Alison, he seems genuinely happy on his son's behalf, showing that he may not be so bad after all. So it's up for interpretation whether he didn't invite Will to his wedding for assholish reasons, or if he did it to protect the socially awkward Will from humiliation from socializing with that many people. Of course, there's always him suddenly Will's mother to marry a woman who could be Will's big sister, but that tale is told from Will's subjective point of view. All in all, Mr. Mackenzie probably is flawed, but it cannot be discerned if he really is that big of a jerk.
Jay. He cockblocks Simon with Carli, which makes him seen like an asshole. However, given how Carli seems to be only leading Simon on, Jay's actions (backed up by the fact that he tries to set him up with another girl at one point) can be seen as him trying to keep Simon from getting his heart broken by Carli, which does happen.
Although Simon is supposed to be the Nice Guy character he frequently behaves like a total Jerkass. The worst examples of his behaviour being lying about Neil's dad molesting him to get out of trouble for skipping school, showing exasperation rather than sympathy with his mother when she is crying over her seperation from his dad, telling Will he should pretend to like a girl he doesn't in order to get a blow job, as well as showing no concern when Will has a very frightening drug trip, where Will begs him for help and Simon tells him to fuck off so he won't mess up his chance with Tara.
Although with the last one, this is Will we're talking about; Simon probably thought Will was just being melodramatic, as usual.
Similarly Will despite being a character viewers are encouraged to root for can be quite a nasty character such as when he knocks out his elderly neighbour, almost ruining a school charity night for an ill student (until a girl he fancies asks him to take part), stealing an elderly womans wig and showing little sympathy for and humiliating a girl whose father has just died (Though, to be fair, he wasn't aware of this).
Although one should add that said ill student (Alistair) earns almost no sympathy himself, milking his illness for the sake of additional female attention and later wishing a serious illness upon Will.
Ensemble Darkhorse: The inimitable Mr. Gilbert. Greg Davies so embodies a teacher who is hilariously tired of his idiot students so much, he starts to turn up a little more often during the show. (Likely because Greg Davies actually used to be a teacher.)
All over the place. Specifically, their goal of having sex is pretty much ruined every time by their own actions.
Will would have lost his virginity to Charlotte if he had even the most basic knowledge of how to have sex. Later, he even has a pretty punk girl come up to him and flat out tell him she wants to have sex with him, and suddenly he feels like 'sliding' around a lame dance hall party in his socks which turns her off completely. Finally, he also blows it with Kerry who is more than willing to sleep with Will before he coldly tells her to go away at Neil's birthday party. To be fair, though, he had no interest in Kerry, despite the guarantee of a blowjob.
Simon agreeing to take the guys with him when Tara wants to go to her sister's flat to have sex with him. Without this, Simon gets laid. No question about it.
More minorly, Simon being incapable of realising that when you park the wrong side of a petrol pump, the pump will not reach.
During the movie, when Simon asks what the All Day Boat Party is.
Simon again; when trying to make conversation with Tara for the first time, he continues to ask her if she buys NME Magazine every week even though she's already told him that she does. He only stops asking when she becomes exasperated with him.
The reason he does this is because Neil mentions at the start of the episode that girls like if boys asks them questions. Except for Simon Comically Missing the Point and apparently thinking that asking a girl to repeat herself is a good way of asking questions, it is also something of an idiot ball to take advice from Neil.
Memetic Mutation: Tons of examples. Try counting how many Facebook groups there are titled after quotes from this show. Lampshaded/discredited by Simon Bird (Will's actor) during a stand-up routine he did on the student circuit. Before going onstage, he set up a presentation telling the audience what hosts of gameshows are supposed to do. "And now for things gameshow hosts DO NOT do: Spout out quotes from The Inbetweeners. Things gameshow audiences DO NOT do: Shout out quotes from The Inbetweeners. Such as: Clunge. Bus Wankers. Football Friend. Right, that's all you're getting!"
Moral Event Horizon: Although Alistair is partially disabled due to a previous kidney failure and comes across as a bit of a selfish prig, it's when he wishes a serious illness upon Will that he really becomes irredeemable.
Most Annoying Sound: In the movie, the football chanters on the bus. Will develops a hatred of Burnley as a result.
Squick: In the Big Damn Movie, Jay is caught masturbating. By his mother. And his prepubescent sister. Wearing a diving mask. And oven mitts. And using slices of ham. Ham. As in: slices of the dead flesh of animals. He's practically made of this trope.
Protagonist Centred Morality: Carli kisses Simon to make another man jealous? She's the bitch from hell according to most viewers. Simon encourages Will to pretend to like a vulnerable, grieving girl he has no interest in just to get oral sex? He's still viewed as a nice guy.
It goes beyond that in Simon's case; Simon set Will up with the girl - Kerry - before Will had a chance to so much as make his mind up about it, and encouraged Will to try and like Kerry not so much for his own benefit as to please Kerry's friend Tara - who also happened to be Simon's girlfriend.
Will (narration): "It was clear tonight wasn't about me at all, and if he thought it would make Tara happy, Simon would have set me up on a blind date with a plastic bag full of his own shit."
Also Nicos, a very minor character in The Movie who is Alison's boyfriend. When Alison finds him having sex with another woman, she is enraged, gravely disappointed and immediately dumps him. Will agrees with her that he is a Jerkass. That's fair enough, since cheating is not okay, but one thing is not noted: Right before Alison caught Nicos cheating, she was teasing Will (possibly flirting), stripping naked in front of him and letting him touch her bare breasts. Unless one only counts actual intercourse as "cheating", Alison certainly wasn't the most faithful girlfriend around either. But no-one bats an eye at her acts.
Wangst: Will is guilty from time to time, but the real expert is Simon.
The Woobie: Simon: a good portion of his suffering may be self inflicted, but a lot more of it comes out of Carli leading him on and the other three pressuring him into things he otherwise refuses to do.
Will gets a turn when Charlotte just dates him to get back at Donovan, and when Simon tells him this he refuses to believe it and storms off in a huff...only for his heart to get broken when Charlotte goes on a Blind Date-esque show at school, leaving Will to run off crying to his mum.
Jerkass Woobie: Jay. He's a little stuck up and arrogant, but clearly has several emotional issues.
Not to mention that his dad is disgracefully cruel to him at times.