Keeping Secrets Sucks: Joey in the arc when Chandler and Monica are keeping their relationship secret. It gets especially hard when he has to take the fall for them when they almost get caught - repeatedly. After one Embarrassing Cover Up too many, he turns the tables by "revealing" to everyone that he'd slept with Monica and she was obsessed with getting him back in the sack.
Kick Me Prank: This is one of the many pranks Rachel teaches Ross's son, Ben.
Lamaze Class: Once subverted when the pregnant Carol is the one unable to attend, so the classes are taken by her ex-husband Ross and her girlfriend Susan. Hilarity Ensues as the two argue over which of them should be the "woman".
Romantic False Lead: When Ross confesses to Chandler's mother (who is a romance novelist) about being jealous of Rachel's boyfriend Paolo, she soothes him by saying "the guy is a secondary character; a complication that you eventually kill off"
In season six, when Monica and Chandler decide to live together, Monica gives him a key to her apartment. Chandler responds, "This door hasn't been locked in five years, but why not."
In the first season, right when Ross is about spill his feelings to Rachel, her former fiance Barry bursts into the apartment to say he's still in love with Rachel, causing Ross to complain aloud, "OK, we have GOT to start locking that door!"
Limited Social Circle: In one episode, all six characters are sitting in Monica's apartment, when there's a knock on the door. Everyone looks utterly confused; no one says anything, but you can tell they're thinking, "if we're all already here, who the heck is it?" Phoebe is even shown pointing at each of the characters, counting them, just to make sure.
In season five, Monica, Joey, Chandler and Phoebe discuss a party for Rachel
Monica: We could have a dinner party and just invite her close friends.
Joey: Ross! We're having a surprise party for Rachel!
Ross: (from the bathroom) Okay!
Ross got mugged by a homeless person who is a friend of Phoebe's. She says "I'm sorry if I have friends outside the six of us".
It's A Small World After All: Throughout the series, the gang bumps into Janice (Maggie Wheeler) often. In her final apperance, near the end of the series, Janice makes a cameo in the neighbouring house of the one Monica and Chandler are buying. Chandler lampshades the unlikelihood of bumping into her every now and then.
Janice: What a small world!
Chandler: And yet, I never run into Beyoncé.
One-Hour Work Week: One Cold Open features the characters bitching about how their employers hate them. Joey: "Maybe it's because you're in a coffee shop at 11:30 on a Wednesday morning?"
Another Cold Open in the premiere of season 3 sees the cast walk into the coffee house and see that another group of six friends (writers of season 3) has taken their spot on the couch. Chandler notes, "Huh," and they turn around and walk out.
Later in the series, you can occasionally see a "Reserved" sign on the table in front of the couch as an explanation of how they manage to always get "their" spot.
The very last joke of the series:
Rachel: Do you guys have to go to the new house right away, or do you have some time? Monica: We've got some time. Rachel: Okay. Should we get some coffee? Chandler: Sure. (beat) Where?
The characters often pointed out minor continuity quirks:
In season four, Chandler offers to get Rachel a date.
Rachel: Hang on, now. I've been single before, how come you didn't offer to get me a date then?
Chandler: Well, I have a girlfriend now, so I'm happy. I no longer need to deprive others from being happy.
In season six, Rachel needs to move out and find a new place to stay. She asks Phoebe if she can stay with her, but Phoebe says she already has a roommate. The others immediately point out that they have never heard of said roommate; Phoebe HandWaves this by saying they never listened when she was talking about her.
Chekhov's Gun: "TOW The Poking Device". Joey makes a poking device out of chopsticks he'd been saving for no reason.
When Rachel's mom came to visit and tried to relive her youth, Rachel asked why her mom couldn't have just copied her hair style. This was a jab at the popularity of Rachel's hair style at the time.
In the second season episode, "The One With Five Steaks and an Egglpant", Chandler gets laid via a convoluted sitcom shennanigan. He had to give the girl Ross's number because he couldn't give her his number because she thought his number was Bob's number. After Chandler explains this, Ross asks, "And what should I do if Mr. Roper calls?"
Soon after Rachel gives birth, she can't decide what to name her daughter. When Monica tells her that she plans to name her own future daughter Emma, Rachel likes the name so much that Monica lets her have it.
Later, when the woman giving birth to the child they are adopting then has a second child (unknown twin), they name the boy after Monica's father and the girl after the childrens' birth mother, Erica, despite the fact Monica has thought up a ton of names beforehand.
Leave the Two Lovebirds Alone: After everyone (finally) finds out about Monica and Chandler, Joey quotes this trope word for word. Ross isn't amused.
Less Embarrassing Term: Ross refers to his shirt as being "sort of a faded salmon color", when it's actually pink.
Friends also had an episode where Joey, based on fashion advice from Rachel started carrying a "unisex bag". Everyone else called it a purse.
Also subverted as Joey loved his "man's bag" despite what others think, he only got rid of it because it started to affect his work (and switches to a backpack instead).
Played with as Rachel is also naive, sweet and the baby of the group, while Monica is more feisty, independent, and a lot more cynical. So it goes both ways.
'TOW The Flashback' shows when Phoebe and Monica were roommates Phoebe, with her ditzy, hippy nature was light feminine and strong-willed, neurotic Monica was dark feminine. (This clash eventually led Phoebe to move out, though they stayed best friends).
Joey: Heh. Let me get this straight. He got you to beg to sleep with him. He got you to say he never has to call you again. And he got you thinking this is a great idea? Phoebe:(weakly) Uh-huh. Joey: This man is my god!
Like an Old Married Couple: Chandler and Monica at times. A hilarious scene has them seriously discussing how to organize their CD's while Rachel, who has actual romantic problems, almost explodes with frustration.
Chandler: Well, if we’re gonna do that we should come up with some kind of order. Y’know alphabetically or by genre?
Monica: Hmm, I don’t know. We really have to talk this through.
Rachel: Oh my God!! You guys have such problems!! I feel so terrible for you
Like Brother and Sister: Joey and Monica in later seasons. Mainly because Monica gets together with Chandler, who Joey considers his "brother" and the trio form a mini-family within the True Companions. (Monica feeds Joey for years, they include a 'Joey Room' in their new house and frequently act as his older siblings).
He's the only character who actually married his older love interest, but there were other instances in the show, like Elizabeth and Ross, or Monica and Richard. Or Monica and Young Ethan (TOW The Ick Factor.)
Limited Social Circle: This show is probably the most obvious example; the six friends barely seem to know anybody other than their families and each other. And their Girl of the Week, of course.
This was lampshaded in one episode. The main characters are all hanging out at Monica's apartment when someone knocks at the door. Everyone is stunned for a moment, and Phoebe actually counts to make sure that, yes, they're all already there. No one says anything out loud, but you can tell they're all thinking, "If we're all here, who the hell is at the door!?"
Another time, Monica and Phoebe were the apartment and the phone rings. Phoebe says it can either be Chandler, Joey, Ross or Rachel.
Yet another time, when Chandler suggests to Joey, Phoebe and Monica they have a surprise party for Rachel 'and invite all her close friends', Joey just has to yell to Ross in the bathroom...and they're all invited.
Another episode has Chandler, making up an excuse to leave, say he's going to meet up with some friends. When he's gone, a confused Joey asks, "He has other friends?"
Whenever the friends do try to become friends with other people, it usually never lasts because the friends or the new friends don't like each other. An example of this is when Joey gets a female roommate and leaves after a few episodes because she couldn't stand Monica and Chandler and Joey refused to ditch them.
Literally Loving Thy Neighbor: Monica and Chandler live across the hall from each other for years before falling in love. Their two apartments are basically treated as one open-doored house for everyone. When they do move into together its hard to tell what's changed.
Local Hangout: Central Perk, conveniently located on the first floor of the gang's apartment building.
Lonely Together: Monica and Chandler have a moment in Season 4. Chandler is stuck in his apartment listening to Kathy (who he's in love with) and Joey have sex, and Monica is boyfriendless and sick. On finding each other wearing pj's and wrapped in blankets, they curl up together in shared misery.
Long Distance Relationship: Monica and Chandler in Season 9, when he's transferred to Tulsa. It doesn't last long as Chandler hates his job and misses Monica so much that he quits.
Longing Look: Ross did this to Rachel a few times in the first season. Chandler and Joey always teased him about it. "Could you want her more?"
Monica and Chandler do this to each other during their Secret Relationship. (As they couldn't act like a couple in public). Noticeably when Rachel wonders why Monica won't go on a double date and doesn't realize that Monica is busy staring right at Chandler as she speaks.
Also Chandler towards Monica in the Season 5 finale when he thinks she still loves Richard. A brief scene has him watching her, almost saying something and then quietly walking away.
There was also the Fonzie-obsessed doctor who delivered the triplets.
Love Confession: When Chandler and Monica secretly become Friends with Benefits, one Thanksgiving ends with Chandler and Monica falling out. To cheer him up, Monica tries putting a cold turkey on her head complete with sunglasses, hat and a ridiculous dance. Laughing, Chandler exclaims, "You're so great! I love you!". Played with in that Monica is pleased but Chandler is so freaked out by his own confession that he immediately takes it back and refuses to admit he ever said it. In a later episode, Phoebe and Rachel catch on and conspire to break Chandler into confessing he and Monica are Friends with Benefits. When Chandler finally snaps, his confession is more than anyone was expecting.
Chandler: "Okay! Okay! Okay! You win! I can't have sex with you!"
Phoebe: "Hah! And why not?!"
Chandler: "Because I'm in love with Monica!" [Reacting to everyone's shock] "Love her! That's right! I love her! I love her! I love you, Monica."
After Chandler and Monica have upgraded from friends to Friends with Benefits for a while, a falling out between them one Thanksgiving leads Monica to don a turkey on her head, complete with sunglasses, hat and a funny dance, to try and cheer him up. Laughing, he exclaims, "You're so great! I love you!". His amusement almost immediately dies into shock as he realises what he just said and what it means, and he freaks out so badly he takes it back. It takes several more episodes before he's willing to actually admit it properly and stand by it, and even then, Phoebe has to break him into confessing it.
Chandler also describes an off-screen example, when they were dancing together and he realized his feelings.
Chandler: "It was the first time I knew that you...you were the woman that I wanted to dance all my dances with."
Happens in the finale with Rachel's answering machine message to Ross after rejecting him at the airport. She's assuring him that she loves him as a friend, "I love you, I love you, I love you. What am I doing? I love you!" You can actually hear her realize on the third "I love you" that she means it romantically.
Another Rachel example, from when Ross was about to marry Emily:
Rachel: I'm not going to Ross's wedding because he is my ex-boyfriend and that would be really uncomfortable. Not because I'm still in love with him! I mean, hey, y'know, I like Ross as much as the next guy. You know, clearly I have feelings for him, but feelings don't mean love! You know, I mean, I still have loving feelings for Ross, yeah! But, I have... I have, you know, continuing feelings of love, but that doesn't mean that... that I'm still in love with him. You'know? I have... I have sexual feelings for him, but I do love him... Oh! Oh my God! Oh my... why didn't you tell me?
Love Hurts: Ross and Carol. Ross and Rachel. Joey and Rachel. Phoebe and David. Monica and Richard. Chandler and Kathy.
Subverted with Monica and Chandler who are blissfully happy together and end up Happily Married. Also Phoebe and Mike.
Nicely subverted in TOW The Girl From Poughkeepsie. Ross is torn between two women: One he really likes but lives two hours away and the other he doesn't like but lives just up town. He ultimately decides not to date either one of them.
Lying Finger Cross: In the episode "The One Where No One Is Ready", Joey and Chandler have a very long argument about who gets to sit on a chair, during which this happens:
Chandler: Well, Joey, I wrote a little song today. It's called: Get Up.
Joey: All right! You can have the chair.
Joey: Oh my, would you look at that! (holds up crossed fingers)
Lyrical Dissonance: London Calling by The Clash playing over Joey and Chandler's tourist hijinks in London. Great song, mentions London... not exactly, y'know, comedic.
Magic 8 Ball: When Ross is faced with either divorce or cutting Rachel out of his life he resorts to consulting an 8-ball. His friends think the idea is ludicrous (except for Phoebe), but they can't come up with anything better. It keeps displaying the "ask again later" message.
While everyone in the show tend to act childish at some point, Ross is the worst one of the group. He usually resorts to petty revenge to get back at Rachel whenever they break up from their on again off again relationship (dating women just to make Rachel jealous) and gets into childish fights with his sister, Monica, such as hogging the TV or calling her childish names. For the latter, Ross thought his squabbles with Monica as they grew up together was harmless fun and that is why he kept doing it well into adulthood until Monica confessed that she hated Ross when they were kids because of his bullying.
Joey is almost as bad in this regard. He constantly mooches off Chandler (with everything from rent payments to acting classes), he refuses to maintain a steady romantic relationship even when he's well into his mid/late-30's, and he's hopelessly idealistic about his acting career despite clearly being a pretty lousy actor.
The show also had the episode "The One With The Rumor", where it was revealed that Ross made out with his librarian in high school, she was 33 years older than him. Not really a Romance Relationship, though.
Meaningful Background Event: In "TOW Chandler in a Box", after Chandler kissed Joey's girlfriend, the Magna Doodle in their apartment is covered with "I'M SORRY"s from Chandler.
Meat Versus Veggies: Phoebe is a strict vegetarian, which is sometimes teased by the group. She was temporarily forced to eat meat while pregnant due to pregnancy cravings and when she met Mike's parents, she attempted to eat veal in an effort to make a good impression. It made her sick instead. Monica also commented that she was so in love with her gay husband that when he left, depression drove her to eat a cheeseburger. This story dramatically shocks the rest of the group.
Ross buys one of these. Too bad it's so small it gets stuck in the parking space. Why they couldn't have grabbed some of their 24 Hour Party People friends and just carried the thing out is difficult to understand. He also quickly abandons the car when an old, bald gentleman shows up driving the exact same car.
Well, they tried carrying it out. Also, Ross offers to sell the car to Joey after the bald guy shows up. Joey passes.
In an earlier episode, Ross and Monica's father mentioned buying a Porsche when he turned fifty. A few seasons later he later gave it to Monica (as an apology for using the boxes with all her childhood relics to block flooding water in order to protect the car).
"The One with Chandler's Work Laugh" features Ross agonizing over telling Chandler that he had a brief relationship with the latter's ex-girlfriend, Janice. Finally, at the end, Ross confesses and Chandler openly indicates that he doesn't care, what with having no lingering feelings for Janice.
"The One Where Phoebe Runs" features this trope again, when Chandler moves Monica's things to clean their apartment and can't remember where they all go. After an episode of his agonising over what she will think, she returns home and seems ready to blow up at him, though in the end she just thanks him for trying to be nice and do her a good thing by cleaning up for her.
In "The One Where Ross Can't Flirt," Rachel borrows and loses an earring that Phoebe had borrowed from Monica. They spend the entire episode agonizing over it, until Phoebe decides to take the blame. She fesses up, and is instantly forgiven. Seeing this, Rachel admits that it was really her fault, expecting to be forgiven too. She isn't. This is probably because she is said to have already borrowed and lost many of Monica's things.
Misplaced Accent: In-universe. Joey evidently had vocal training to learn how to do an American Southern accent for a play about the American Civil War, but it ends up coming out as a Jamaican accent.
Miss Conception: Monica and Chandler want to adopt from a woman who is still pregnant with the child. They inquire about the father who she reveals is one of two choices: one golden boy and one jail hound who murdered his own father with a shovel (Shovelly Joe). They (especially Chandler) worry about the father-murderer choice until Monica discovers that the act she committed with him was not something that could get you pregnant.
Mood Whiplash: The show occasionally does this, and never more than in the episode "The One With the Morning After" which deals with the fall out of Ross sleeping with another woman behind Rachel's back after believing she's left him. Even though it's a fairly serious episode, the majority of it still has a few hilarious moments such as Ross and Rachel taking a brief break from their fight to order pizza and Rachel intentionally ordering anchovies mixed in with the toppings and sauce because she knows Ross hates them. However, the very last scene completely abandons the humorous aspect and goes completely serious. Even the brief moment where we see the remaining four other characters still trapped in Monica's back room is suddenly much more serious as they're all somberly listening in to the conversation, with Monica and Phoebe even breaking down into tears as they all realize that their two friends' relationship is over.
"The One With The Fertility Test" also has this. Most of the episode revolves around usual hi-jinks and Chandler freaking out about 'doing it in a cup'. Right at the end of the episode he and Monica discover they probably can't have children and the scene fades out with them sobbing in each other's arms. It's a punch in the gut that leaves you reeling and wondering what happened to so-called 'comedy'.
A lot of episodes with Monica and Chandler involve this, as the writers balance what is a genuinely sweet, heart-warming relationship and comedy. Their engagement episode goes from an amusing Zany Scheme to Chandler breaking down thinking she's left him and a gut-wrenching proposal, to the others coming in to crack some jokes, and then back to them dancing quietly together. Hell even their wedding vows switch between their tender declarations of love and Joey's messing up the order of service.
Monkey Morality Pose: In "TOW The Fake Monica", Chandler, Ross, and Joey assume this pose upon realizing that Marcel has to go to a zoo.
Monochrome Casting: The show rarely has any significant minority characters, though there is the occasional exception. The pilot featured a prominent black character as a comic foil for Monica, but she was written out to focus on the core cast.
The creators of Friends did take in the criticism and therefore cast a black woman as a love interest for Joey and Ross in the later seasons. While it was nice of them, it also was kind of odd, considering the Monochrome Casting of the love interests prior to her.
In the second and third season, Ross dated Julie, a Chinese woman.
Mystery Meat: Mockolate. Monica is asked to come up with recipes for it while the company awaits FDA approval. It doesn't. The first red flag is that real chocolate doesn't crumble when handled. And the taste?
Phoebe: Oh, sweet lord! This is what evil must taste like!
The same company also makes Fishtachios, which is exactly what it sounds like. And should be avoided by people who are allergic to cat hair.
Naked People Are Funny: There's the 'Ugly Naked Guy'. This is an interesting example as he is almost never actually seen* In the season 5 episode "The One Where Everybody Finds Out" we finally get to see him in the flesh, although only from behind but only described by whichever friend is spying on him at that moment.
Poked fun at in a flashback episode, where the girls mourn the fact that "Cute Naked Guy is really putting on a lot of weight".
Joey revealed in one episode that he cooks while naked.
Joey: "Oatmeal, toast... Nothing that spatters."
"Why do you think it takes me so long to answer the door?"
Joey: You know... lending friends money is always a mistake. Monica: But Chandler lent you money! Joey: And I think he would tell you it was a mistake.
In an inversion, Chandler spends an episode desperately trying to lend Joey money, but Joey doesn't want to owe him anything - presumably because of this trope. And thus was bornthe Game of Cups.
New Year Has Come: The show had a couple of New Year's episodes, the most notable one being where Chandler kissed Joey.
"The One With the Routine" has Monica and Ross attempting to get on TV whilst on-set filming Dick Clark's New Year's Rockin' Eve.
Never My Fault: Rachel tries to make Ross take full responsibility for their break-up, even though, as Ross puts it, "It took two people to break up this relationship."
In response to that, Rachel said, "Yeah, you and that girl from the copy place." She was claiming that Ross's cheating on her (which Ross vociferously insisted wasn't really cheating because they were "on a break") was the sole reason for their breakup, even though there were numerous problems in their relationship well before that. Or that she had the guy Ross was jealous of come over to comfort her not an hour after their big fight (and he answers the phone when Ross calls to try and patch things up). Other occasions have her claiming Ross begged her for sex even though she came onto him.
Ross has shades of this himself, like when he smoked weed and blamed it on Chandler. (And when his parents found out claimed he was 'tricked into it') A major reason their relationship kept failing was they both refused to take responsibility for anything and blamed the other. This probably stems from the act they were both extremely spoiled as children. In the series finale, they both sort of acknowledge this and resolve to stop being stupid.
Nice Guy: All three of the guys qualify in different terms. Ross is Adorkable and romantic. Joey is incredibly loyal and a great friend. And Chandler, despite his sarcastic defence is a total sweetie, constantly puts his friends, and later girlfriend ahead of himself, and comes out with some of the most thoughtful moments in the series. Check the heartwarming page for (numerous) examples.
Plus the writers ensure they're all interesting, flawed characters; Ross has past issues with divorce, Joey is a bit of a casonova and Chandler is deeply insecure and scarred from his childhood. They're still adorable.
Phoebe's husband Mike and her first serious love interest, David "the Scientist Guy".
Also Ross and Monica's father Jack Geller.
Monica's season 2 boyfriend Richard Burke is one of the nicest characters on the show.
No Bisexuals: Prior to the start of the series, Ross's wife Carol comes out as a lesbian after seven years of marriage to a man - which is perhaps not in itself unusual, particularly in a less than gay-friendly early '90s context (especially since it's later made clear that her parents are at least vaguely homophobic). However, it's clear that she and Ross still enjoyed a sexual relationship together for a while after she got involved with Susan - not only does he explicitly bring up on one occasion how they had "some good times before she became a lesbian... and a few afterwards, as well", but a flashback to exactly one year before the pilot episode reveals that their son Ben must have been conceived at least three months after she admitted to seeing Susan. However, bisexuality is never brought up, and everyone accepts that she's exclusively gay.
In one episode Joey refers to Ross as a guy who "married a woman who was nearly a lesbian, and then pushed her over the edge". Granted, it's intended as an insult and it's said by Joey, but Carol being bisexual would make a lot more sense.
It might be that Carol is portrayed as gay to make her more sympathetic. An openly bisexual woman cheating on her husband, whether with a woman or man, and eventually leaving him for her new lover just wouldn't be as likable as a repressed lesbian who's dealing with her sexual awakening and the breakdown of her marriage in the best way she can.
Also, Phoebe is shown to be attracted to women on occasion, and seems to be seriously considering asking out Ross and Monica's ridiculously beautiful cousin Cassie (although it could be argued that this is more a case of Even the Girls Want Her / If Its You Its OK). She is, however, openly admiring of attractive women on a number of occasions. Despite this, she's only ever shown dating men.
Nobody Thinks It Will Work - What Does She See in Him?: Both Rachel and Phoebe look down on Monica and Chandler's as a couple, but as neither of them manage to establish a successful relationship until the end of the series, and Monica and Chandler are very happy and well-suited, they come across looking like jealous jerks rather than friends with legitimate concerns.
Averted with Joey who thinks they're great and 'going to last forever'.
Monica: That was not an incident! I was gesturing and the plate... slipped out of my hand.
In another episode Phoebe references the time a peacock bit Chandler in the zoo. This is actually mentioned in two separate episodes in the first season, suggesting that the writers were planning on making it a Running Gag, but then decided against it.
Another has Ross and Chandler getting ready for a night out with their college buddy Gandalf. One of them states that he has Canadian money, a snakebite kit and an extra pair of socks. The other warns him that it won't be exactly the same as last time.
"Vomit tux! VOMIT TUX!"
The time Phoebe stabbed a cop.
Phoebe: What, he stabbed me first!!
Phoebe's brother laments the various misfortunes in his life, including the time he got arrested for stealing those birds and "that punctured lung thing."
Rachel finds out from Phoebe that Chandler owns a jewellery box when the pair are racing against the clock to find a missing earring. Due to lack of time, Phoebe refuses to explain the story of why Chandler owns one... or how she knows about it.
On the Vegas trip, when Phoebe is told that being married in Vegas is as binding as being married anywhere else she says, "Oh my god. Oh My God! OH MY GOD! Meh..." (Word of God is that the audience is supposed to think she got married on some prior trip to Vegas.)
Phoebe appears to have a lot of these in her past. She once said, "There's so much you don't know about me."
In "TOW Where Phoebe Runs", what "guy problem" did Chandler have and why did it need medication?
Not Important to This Episode Camp: Happens to Ben and later Emma a lot. Justified with Ben, since Carol and Susan are his primary caregivers. However, Emma was always explained as being at somebody else's house.
To be fair, Emma is represented in a lot more episodes than a lot of TV babies. She's just the quietest baby ever. There are a lot of episodes in one of the apartments, or Central Perk, where a bassinet or carseat is present, and we never see what's in it. Whatever it is is completely silent, and everyone ignores it, so maybe Emma just sleeps a lot.
Ross also mentions interacting with Ben a fair bit in episodes where he does come up (being familiar with Ben's current developmental phases and whatnot), so it can likely just be assumed that most of his interaction with Ben happens offscreen, since it's not a hang-out-with-friends activity.
Not in Front of the Kid: When Monica and Chandler are trying to have a baby, they babysit Phoebe's triplets. They start to make out and Chandler says he's not comfortable doing it in front of the B A B Y. Later, Joey comes in and says "You can't have sex around a B A B I E!"
In an earlier episode, Phoebe is feeling guilty about spending time with her biological mother and imagines that her mother has been reincarnated as a cat.
Phoebe: I think someone's upset that there's a new mom at the B E A C H. [Beat] I just spelled the wrong word.
When Phoebe gets Monica and Chandler a Ms. Pac-Man machine as their wedding gift, Chandler wastes no time in making dirty high-score initials. With Ross bringing Ben over, Monica orders the dirty initials removed; when Phoebe fails her last attempt to remove the final dirty name with a high score, she launches a foul-mouthed tirade right when Ross and Ben walk in, forcing Ross to put "earmuffs" on Ben.
Janice is grating on all of the friends and they all dread seeing her and even hearing her voice. In short, she annoys them. However, in the short time that Ross dated Janice, Ross' constant whining and complaining managed to get the annoying Janice to be annoyed with Ross' negativity. This completely shocks Ross and he lampshades it:
Ross: I annoy YOU? Janice?
Chandler realizes this about him and Mr. Heckles in TOW Heckles Dies.
In "The One With the Morning After", in an effort to cover up his trail from Chloe (with whom he'd had an affair) to Rachel, Ross speaks with Chloe's co-worker, Issac, who is more than eager to help Ross.
Ross: Listen, can you keep this information to yourself?
Issac: Aw, no problem dude. Y'know we got to look out for each other. We’re the same, you and me.
Ross: Actually, no, we’re not.
Issac: Yeah, we are.
Ross: No, we’re not.
Issac: Yeah, we are.
Ross: No, we’re not!!
Issac: Okay, we’re not.
Issac: But, we are.
Not With Them For The Money: Monica towards Pete. Despite his offers to buy her a restaurant (and escape her horrible job) and Rachel's encouragement to date a billionaire she turned him down until she developed genuine feelings. This contrasts with former Gold Digger Rachel, who encourages her to date him anyways because he's a billionaire.
No Sense of Personal Space: The gang as a whole, justified given how close they are to each other. However in early seasons Monica and Chandler were worse than the rest, (at least with each other), frequently cuddling on the couch, absentmindly stroking each other, curling up and watching movies, draping across each other, holding hands, hugging while half-dressed.... When they started their Secret Relationship they actually seemed less cuddly in public! It does explain how they kept it hidden for so long though.
Monica also does quite often with brother Ross for some reason; in "The One Hundredth", she actually sits in his lap during the last scene.
Not So Great Escape: Ross does this several times in one episode of Friends. When he is in a secluded log cabin waiting for his girlfriend, Elizabeth, to get back from the shop Elizabeth's dad, Paul, turns up with Rachel. Ross, with his trousers around his ankles, hides under the couch. Later he is discovered by Rachel, who covers for him and gets Paul to leave the room. Ross takes the opportunity to move to another room, which turns out to be Paul's bedroom. When Paul comes in later Ross hides behind the door, then falls to the floor and crawls under the bed, from where he witnesses Paul's embarrassing routine in front of the mirror. When Paul leaves Ross begins to climb out of the window, but is discovered when he is half-way out.
Then in another episode, Ross breaks into his ex-girlfriend's apartment to retrieve his favourite pink salmon sweater and is inside when aforementioned girlfriend comes home with a date. He is then forced to hide under the couch on which they are currently making out. Eventually he gets bored and starts reading a magazine.
Nothing Is the Same Anymore: Half-way season 3, when Ross cheats on Rachel the dynamics of their relationship literally never go back to be the same.
Rachel: I can't... You're a totally different person to me now. Now this has changed things... forever...
Later in the show, Ross gets married and Monica and Chandler sleep together. Ross's marriage ends almost immediately, and they keep teasing a quick and quiet end to Monica and Chandler's relationship. But they continue dating, stay together and end up getting married. Their marriage is the start of the Friends 'growing up' and tellingly the series ends with them moving to the suburbs with their children.
Rachel's pregnancy at the end of Season 7.
Nuclear Candle: In one episode, there's a blackout, and the friends are bringing in candles for light. Later on, all the candles but one are extinguished, and yet the light level is almost the same. One of the characters then blows on this last candle extinguishing it, and everything goes dark.
Nude Nature Dance: When Phoebe suggests a relationship cleansing ritual, it turns out you can either go the burnt offering route or the "dance naked with sticks" route. Rachel and Monica opt for the first.
Object Ceiling Cling: Monica is making a milkshake, but Rachel says something that surprises her, making her lid hand slip, splattering bananas on the ceiling. It doesn't come down until Monica mops it up.
Oblivious Mockery: Rachel and Monica discover a message on Ross's answering machine from Emily, Ross's ex-wife. Emily is having second thoughts about her upcoming marriage to someone else. They debate whether or not to erase the message - Monica wants to, Rachel doesn't.
Monica: All right, look. She's obviously unstable, okay? I mean, she's thinking about running out on her wedding day.... (In the first episode, Rachel ran out on her wedding) Okay, fine, but... I mean, look at the position she's putting him in. I mean, what's he going to do? He's like... Ross is going to run over there on the wedding day and break up the marriage? Who would do that? (Rachel did this when Ross & Emily were getting married).... Okay, fine. All right? But that's... you know, that was different. Although it did involve a lot of the same people.
Oh god, Ross and Rachel. Their relationship drama lasted from the first five minutes of the pilot to the last five minutes of the finale, so even the characters themselves were sick of it.
Thankfully averted with Monica and Chandler. They manage to get together, fall in love, get engaged, married and start a family without breaking up once and still remaining funny and popular.
Oh Crap: In "TOW The Embryos", during the trivia game with the animals/apartment on the line, Rachel and Monica when presented with, "What is Chandler Bing's job?" Also, Rachel's "NOOOOO!" catchphrase.
Old, New, Borrowed and Blue: When Chandler and Monica decide to get married in Vegas on impulse, they shoplift a blue sweater to count as something new, borrowed, and blue. For something old:
Chandler: I have a condom in my wallet that I've had since I was twelve. Monica: That'll work! Chandler: I don't think so.
Phoebe gets married outside in the snow - when asked if she's going to be cold, she says "I don't care. I'll be my something blue!"
One-Hour Work Week: Chandler's job in early episodes of Friends is subject to a Lampshade Hanging in one episode, where the deciding question in a trivia contest is "What is Chandler Bing's job?" Incidentally, it was Statistical Analysis and Data Reconfiguration until he got a job in an advertising firm. Even when Chandler and Monica are a couple she can't remember what he does. This is Lampshaded in one episode, where the Friends note that their bosses don't seem to like them... at which point Joey points out that this may be because they're hanging out at a coffee house at 11:30 on a Wednesday morning.
Made more fun by the fact that Joey is one of two people in the group - the other being Phoebe, and even then Phoebe sometimes does hold regular jobs as a masseuse - who works as a free-lancer.
Joey shouldn't be let off the hook either. It was justified when he was a struggling and mostly unemployed actor. However, daily soap opera stars have incredibly long work hours.
Rachel and Chandler the ones with ordinary office jobs appear to take lunch breaks for hours at a time.
Monica has several character arcs about her career as a restaurant chef, eventually becoming Head Chef at a very prestigious restaurant. This is usually a job with 14 hour days, often seven days a week, but she seems to work about as much as Joey when he's unemployed.
Not to mention Ross, who in later seasons is a university professor, a career involving not only teaching but tons of grading papers, tutorials and your own research. He seems to go to campus once a week at most.
One Gender School: Chandler frequently makes jokes about attending an all-boy boarding school when he was growing up.
In another episode Ross & Chandler's party animal friend from college comes to town and they all go out partying. He bails on them, so Ross, Chandler and Joey decide to go out on their own, only to discover that they needed a guy like that to really be able to party hard.
One Steve Limit: On set, Matt LeBlanc was referred to by his last name to avoid confusion with Matthew Perry while shooting.
The One With: Trope Namer. The show referenced this by starting all but a handful of episode titles with the words "The One (With/Where)...", the exceptions being the pilot and the finale, along with a few shows called "The One After...". Additionally, the pilot has an alternate title; it is now listed on IMDb as "The One Where Monica Gets a Roommate" and the Season 1 DVD set also uses that title. The Other Wiki still calls it "The Pilot". The series finale is titled, logically enough, "The Last One". The reason for this is exactly the one seen above in the trope description: so the episode can be discussed in informal conversation without the need to remember the title.
This can result in odd situations where the title won't always correspond to the logical "The One With" name. For example, "The One With The Embryos" is more well-known as the one with the trivia contest that leads to the guys and girls switching apartments.
OOC Is Serious Business: In "TOW All the Cheesecakes", it's revealed that Platonic Life Partners Joey and Phoebe have a regular dinner outing each month, just the two of them, but Joey bails on her once to go on a date. Phoebe is legitimately upset at this, causing Joey to profusely apologize for not realizing the importance of their get-togethers and gives her a Cooldown Hug.
Opening Credits Cast Party: The opening has the characters goofing around a fountain in the park. The odd part isn't that the characters are all together (they almost always are in the show itself), it's that they're apparently having a late-night party in the middle of a deserted park... that has a couch!
And a lamp that's hooked up to the fountain's floodlight!
Fans have attempted to shoehorn this into the show's canon by saying that it was a photo shoot that Joey was participating in early in his acting career. For some reason, they needed five other extras in a hurry, so Joey called up his friends.
The fountain rarely makes an appearance in the show itself.
Distressingly, David Schwimmer's "Mr. Roboto" dance was removed in later versions.
Operation Jealousy: A complicated version: Monica and Chandler have a Friends with Benefits relationship that's clearly bordering on more, but Monica gets asked out. She intended to get out of it but Chandler misunderstands and claims they were just 'goofying' around to protect himself. This prompts a hurt Monica to say yes to the date and and flaunt the guy in front of him. Thankfully Chandler talks to her, explains his feelings and she calls the scheme off.
Opposites Attract: Ross and Rachel; Phoebe and Mike. To a lesser extent Monica and Chandler.
Other Me Annoys Me: Rachel dates Russ, a guy who's remarkably like Ross. Ross finds him completely annoying, being totally unaware that he's basically criticizing himself.
Out of Focus: Ben disappears after season 8, Carol after season 7, and Susan after season 6.