Averted to some extent: They do use realistic sound effects for the games (sometimes), show actual Age of Conan screens, and showed Howard and Leonard boxing in Wii Sports. In another episode, they show some gameplay footage from Mario Kart Wii, and even then, it's not shoehorned.
In one episode, Sheldon sits out in the hall playing Super Mario 64 on his laptop via emulation as he can't use the console in the apartment. The sound effects are entirely correct. However, he also mentions the his mother sent the memory card along with the console. The N64 did have memory cards, but they were only compatible with certain games. Mario 64 was one that saved directly to the cartridge.
While playing Super Mario 64, Sheldon is inside Peach's Castle (according to the music). When Penny asks him a question and they start talking, Sheldon pauses the game, also stopping the music. When Penny's gone and he unpauses, the music that plays is from the middle of one of Bowser's worlds. Possibly averted: Savestates.
Played straight with their Halo matches. The sounds and the commentary rarely match up with any of the games. Makes you wonder if they've ever actually played Halo.
Pśdo Hunt: One early episode had Leonard rush Sheldon out of a bookstore to keep anyone from starting one after seeing him have a civil conversation with a ten year old girl.
Paintball Episode: The guys play on their own time and there is some company activities there with teams divided by department (apparently the pharmacology department were hyped up on experimental steroids). They are generally accurate to the game, using masks that reasonably cover the face and body armor, although they do remove their masks when in a bunker. As common for the trope, they are strategizing and constantly worrying about when their "time" will come.
Invoked by Sheldon's mother to get him back together with Amy. Penny's dad also tries to use reverse psychology to get Penny back together with Leonard.
Mr. and Mrs. Kootherppali's disproval of Leonard and Pryia's relationship. Howard THOUGHT Mrs. Wolowitz was going to have this kind of reaction to his engagement to Bernadette, but she actually really likes her.
Sheldon often views Penny as a substitute for his mother (who is alive, just lives away from him); he wants her to take care of him when he's sick, or sing him a lullaby. This is especially emphasized in the episode "The Guitarist Amplification", when Sheldon runs away to the comic book store, because he can't bear Leonard and Penny fighting, and Penny makes it up to him by buying him a robot and a comic book.
Leonard takes on a fatherly role at times: taking care of his transportation needs, shopping for food and clothing, making sure he goes to bed on time and is often the one he goes to for advice on relationship matters. When he and Penny were dating they served as surrogate parents, when they broke up Sheldon was like a child in a divorce. That led to a lot of Does This Remind You of Anything? dialogue as Leonard and Penny renew their friendship for Sheldon's sake.
Personality Swap: A very mild version, but Penny once dislocated her shoulder and was taken to the hospital by Sheldon. Returning home high on painkillers, she convinced Sheldon to sing "Soft Kitty" to her. Usually the roles are reversed.
There are a few times where the other characters mimic Sheldon's idiosyncratic door knocking, specifically Penny when Sheldon stole her laundry during an Escalating War. Howard uses a recording of Sheldon to do it, tricking Penny into opening the door.
Picked Last: After Penny and Leonard break up, Sheldon is asked whether he's on "Team Penny" or "Team Leonard." He answers, "Whichever team picks last," since that's how it happened when he was in high school (unless there was a kid in a wheelchair).
Made all the funnier by the fact that Sheldon never went to high school to begin with.
Pity Sex: The proxy version. Leonard and Raj hire a prostitute for Howard on a trip to Las Vegas that happens right after Leslie Winkle breaks up with him, though any sex that might ensue is glossed over.
Penny blasted Howard for being a creepy sleaze, hurting his feelings. When she goes to apologize, he tries to kiss her, and has his nose broken. When the guys hassle him about it, he says "The way I see it, I'm halfway to pity sex".
The Plan: "The Good Guy Fluctuation" when Howard and Raj reveal themselves as the pranksters behind the attempt to scare Sheldon at the office. But to paraphrase Homer Simpson, their zany scheme was a front for an even zanier scheme. Anticipating that their relatively tame and cliche hijinks wouldn't scare Sheldon, Howard and Raj seemingly admit defeat in Sheldon's office when a man wearing a mask of the alien from the end credits of Star Trek: The Original Series pops out behind Sheldon's white board, successfully scaring Sheldon. The man unmasks; it's Leonard.
It's a Xanatos Gambit in that they foresaw that their intial pranks would fail but a Kansas City Shuffle in that the initial pranks were a distraction from the true scaring attempt.
Plato Is a Moron: Sheldon compares himself to Isaac Newton in one episode, declaring that "Gravity would have occurred to me without the apple."
Poor Communication Kills: After Leonard and Penny's first date, she confided in Sheldon that she lied to Leonard about getting a community college degree, and swore him to secrecy. Sheldon nearly went crazy holding it in, and told Leonard only when he was drugged up on Vicodin. Leonard assumed Penny was embarrassed over not completing college and tried to show support by giving her a Community College brochure. The problem was Penny didn't care so much about college as she was worried Leonard considered himself too smart for her, and him bringing over the brochure validated her concerns. This is largely the reason for their romantic false start in the second season.
Power Trio: Discussed by the writers at a convention, Leonard occupies a space where he is pulled in two directions: a greater world of human social interaction with Penny and a seclusive world of math and science with Sheldon. It thereby makes Penny The McCoy, Sheldon The Spock and Leonard The Kirk.
Pop-Cultural Osmosis Failure: Goes in two ways, Penny failing to recognize the geeky stuff, and Sheldon & Co. not knowing relatively normal things.
Penny:(reading a trivia game card)Tweety Bird will often say 'I tawt I taw a...' what. Sheldon:(after several seconds of tense, non-verbal communication with Leonard) ...Romulan?
Poor Predictable Spock: Aside from being the only thing anyone picks in Rock Paper Scissors Lizard Spock, Sheldon is always thinking of Spock when playing 20 Questions.
Precision F-Strike: After Sheldon says that Howard's robotic hand is no more than a minor upgrade from fast food animatronics, Howard makes the hand give Sheldon the finger. Subverted since it ended up giving him the peace sign.
Sheldon rarely swears, so when he does it comes as a surprise. He swears more often when quoting someone than of his own accord: "He was very understanding; he said, 'Got you back jack, bitches be crazy'".
Amy invited Leonard to be her date to a wedding and made a conscious effort to be social and engaging, with Leonard not really being good company. Eventually she calls him out on his moping around and said, "I have a kinda-sorta boyfriend who is playing with model trains tonight and you don't hear me bitching about it."
Prehensile Tail: Parodied in an episode as the foursome are playing a group roleplaying game as bad guys approach.
Leonard: They're on my tail! ...But it's prehensile so I can handle them.
All of Chuck Lorre's recent projects, including Two and a Half Men, use and place Safeway products around the set.
All of the gang's shirts are available for purchase (most of them can be found here), as is the periodic table of elements shower curtain.
Warner Bros. owns the show (alongside DC Comics) and the vast majority of comic references comes from DC, and the comic shop the guys frequent seems to only sell DC titles (and Madman.) But Marvel comics, as well as smaller companies and series, do show up from time-to-time. (Perhaps most notably the episode with guest star Stan Lee).
Episode 5x07 had several #1 issues from the September DC reboot. Presumably those issues will be missing the page adverts for this show.
After being syndicated to TBS, the station has two different forms of the trope going; A), using clips from the show and splicing in TBS (sometimes pretty badly), and B) having static shots of the main apartments, particularly the guys' formula boards, where the product placement of the day equals funny/delicious/good (anything from pizza to beer to a service) even if the show doesn't have anything to really do with the product.
Promotion to Opening Titles: The opening sequence doesn't actually give off a cast list but the final shot of the group eating take-out together has evolved a few times but always with the core 5 cast members. In season six Bernadette and Amy are finally added.
Protagonist-Centered Morality: In "The Middle-Earth Paradigm" Leonard picks a fight with Penny's ex-boyfriend, Kurt (Kurt was being a bit rude, but Leonard was plainly the one who started it), deriding him for his unintelligence and provoking him into a physical confrontation but everyone acts like Leonard was the victim and Kurt is a giant asshole.
Puppy-Dog Eyes: Leonard, of all people, manages to pull one off in Season 6 just before Penny was about to give him the break up speech. This is then imitated by Penny, Amy and Bernadette to great comedic effect.
Pursue the Dream Job: Penny aspires to become an actress, and a big TV or film star if possible. She works as a waitress and keeps going to auditions. She had a role in a commercial once, but other than that — no big luck so far.
In "The Plimpton Stimulation", Bernadette. Offscreen, no less. The Bus Came Back: She returned in "The Hot Troll Deviation" becoming a regular character and got back together with Howard. As of the end of Series 5 they're married.
Leonard's doctor girlfriend in the second season. In her last appearance, Leonard was afraid she was getting too close, but the episode seemed to end with everything turning out all right. Then she was never seen or talked about again.
Leslie Winkle, which is lampshaded when Leonard goes to see her and she remarks its been around 18 months since they last spoke.
Random Number God: 5x04 Sheldon decides to let dice make his every pointless decision.
Ranked by I.Q.: Sheldon often uses his IQ as a 'proof' that he's correct. There's also the first episode when Sheldon and Leonard list their combined IQ of 360 as evidence that they can figure out how to get into a locked apartment building. Two girl scouts then come up, ring every bell, and are immediately buzzed in.
Reality Ensues: Penny snapping at Howard over his lecherous behavior towards her. Few women, especially ones as outgoing as Penny, would tolerate it week-in, week-out for years without without doing something about it (either what she actually did or simply refusing to even spend time in his company). It could be viewed as a commentary on how some Running Gags get run into the ground.
Real Life Writes the Plot: Penny was absent for two episodes in Season 4 and was behind the bar of the Cheesecake Factory when she returned. This was to work around Kaley Cuoco suffering a compound fracture in her leg after she fell off her horse and it stepped on her leg.
Leslie Winkle is implied to be this, referring to waking up on a futon with half a dozen strangers as a reason to try and settle down with Leonard.
Penny objects to being perceived this way after Sheldon calculates the number of men she's slept with in her lifetime based on her current statistics. The thing with Penny isn't that she sleeps around but that she really appreciates a physical relationship with her boyfriends, she just seems to have a new boyfriend every other week in the early seasons.
Which was written for the show so not really this trope.
Rearrange the Song: As Theory entered 5 night a week syndication in 2011, Barenaked Ladies' wrote and preformed a number of different versions of the lyrics to the Real Song Theme Tune "The History of Everything" mentioning the cast by name, which aired in short ads shown after the first commercial break.
The one directed at all four guys in "The Nerdvana Annihilation". It caused a Despair Event Horizon moment for Leonard.
(Penny comes in and is upset with the guys.)
Penny: OK! First of all, what you call a gap, was nearly 3 feet wide; I slipped and skinned my knee.
Leonard: Are you OK?
Penny: Azzzzzz! Second of all, the door to the stairway of the other building was locked, so I had to go down the fire-scape which ended on the third floor, forcing me to crawl through the window of a lovely Armenian family, who insisted I stay for lunch.
Leonard: That doesn't sound too bad?
Penny: It was eight courses of lamb and they tried to fix me up with their son.
Penny: Not done! By the time I finally got to work, they'd given my shift away. Yeah, that's right, I lost an entire day's pay thanks to this, this...
Sheldon: Time Machine.
(Penny stares at Sheldon, giving him an evil glare.)
Leonard: The lights flash and the dish spins, you wanna try it?
Penny: No! I don't wanna try it; my god, you are grown men, how can you waste your lives with these, stupid toys and costumes and comic books?! And now that! That...
Sheldon: Again, Time Machine.
Penny: Oh please! It's not a time machine, if anything, it looks like something that Elton John would drive through the Everglades.
Sheldon: It only moves in time. It would be worse than useless in a swamp.
Penny: Pathetic! ALL OF YOU! Completely pathetic!
The one directed at Howard in "The Killer Robot Instability" caused a Heroic BSOD.
Penny: I know you think youíre some sort of smooth-talking ladiesí man, but the truth is, you are just pathetic and creepy.
Howard: Um, so what are you saying?
Penny: I am saying it is not a compliment to call me doable. Itís not sexy to stare at my ass and say, ďOoh, it must be jelly ícause jam donít shake like that.Ē And most important, we are not dancing a tango, weíre not toíing and froíing. Nothing is ever going to happen between us. Ever.
Howard: Wait a minute. This isnít flirting, youíre serious.
Penny: Flirting? You think Iím flirting with you? I am not flirting with you, no woman is ever gonna flirt with you, youíre just gonna grow old and die alone.
Red Alert: Sheldon getting a cold is serious enough to cause Leonard to run out of the apartment in the early hours of the morning, frantically calling everyone so they can bunker down and avoid looking after him.
Reed Richards Is Useless: All of the scientists on the show are fairly accomplished, but to keep the premise from overwhelming the average episode they are unlikely to make any major contributions to science and engineering. As well Sheldon is not going to prove string theory or otherwise get a Nobel Prize because however smart the science consultant may be, they are unlikely to have a Nobel Prize worthy theory in their back pocket.
When Stephen Hawking points out that Sheldon made an error in his mathematics, meaning that his revolutionary theory about the Higgs boson is actually completely wrong.
A Story Arc going through season five and the beginning of season six featured Howard getting the chance to be an astronaut going to the International Space Station. It's an immense accomplishment for an individual and incites some jealousy within the group but the mission was ultimately fairly routine and nothing of real notoriety happened. Part of the character arc involves the reality that he likely won't be recognized at the mall and the emotional high would wear off over time. Many of the astronauts who were on significant missions (such as the Apollo Moon landings) did have issues adjusting to life as the fame wore off and the realization that they would likely never do anything as significant again in their lives set in.
A season seven episode has Sheldon figure out a formula for a new superheavy element that is eventually proven, earning him accolades at work and many articles written about his discovery. In the midst of recording the things that led him to this discovery he realizes he misread a table reading meters rather than centimeters, meaning his math was off by a factor of 10,000. Interestingly, the discovery was legitimate and only worked because of unanticipated reactions between the particles, so Sheldon gets to keep his accomplishment but it drives him crazy that it was a fluke. A follow-up episode reveals that the confirmation of his formula was falsified or improperly tested by the research team. Ironically, because Leonard was the one who found the incongruity and proved the experiment to be wrong HE becomes a minor celebrity and Sheldon's accomplishment shunted to the side.
Relationship Revolving Door: Leonard and Penny have this kind of relationship, full of false starts, set backs, and at least two notable break ups. As of season five they're significantly more stable, but Penny's Commitment Issues have threatened to bring them back to square one a number of times.
Relationship Upgrade: Between Leonard and Penny, at the beginning of season three. They broke up about 3/4 of the way through the season. They get back together in season five.
And, as of 5x10, Sheldon and Amy.
Relatively Flimsy Excuse: In "The Loobenfeld Decay", Sheldon invents a drug addicted cousin as an excuse to avoid attending a show of Penny's. This spirals out of control and Sheldon ends up employing a lab assistant to play his cousin Leo.
Religious Robot: Discussed. When the boys talk about having their consciousnesses implanted into robots, Howard says that his robot would have to stay Jewish because "I promised my mother." The others talk about how Howard would have to power down on Saturdays and have his rabbi discuss with the manufacturer about getting circumcised.
Reluctant Gift: Sheldon wants Howard to accept his apology for inadvertently blabbing to the FBI about Howard mishandling the Mars Rover, so in desperation he gives him that which is most precious to him — his spot on the couch. He offers the cushion to Howard, but is reluctant to let it go at first. Howard barely has the seat a minute before Sheldon asks for it back.
Remember the New Guy: Raj's sister, Priya is introduced in Season four with a full back story explained in exposition, plus a never-before-mentioned romantic entanglement with Leonard.
Retail Therapy: Penny tries to convince Sheldon that buying a new suit will make him less nervous about an upcoming speech.
Penny: Itíll give you confidence. You know, sometimes when Iím feeling all stressed out about something, I go out and buy a cute top or a fun skirt and I have a whole new outlook on life. Sheldon: Donít you eventually realize youíre just the same stressed-out person in a cute top or a fun skirt? Penny: Yeah. Thatís when I buy shoes.
Retcon: In the pilot Penny was made out to be a little bit older (like mid-20's), being that she had broken up with her boyfriend, Kurt, of specifically 4 years. While the relationship and break-up were still maintained Penny's age was made out to be 21 in the pilot and the length of time with Kurt (given she was in high school in Nebraska 4 years prior) was not nearly as significant a part of her life.
Roaring Rampage of Revenge: A literal one in "The Good Guy Fluctuation" by Sheldon, victim of a Halloween prank from Leonard. Early in the episode, Sheldon insists that Leonard open a mailbox, only for Leonard to find junk mail. When Sheldon goes to open the mailbox, an airbag with Leonard's face pops out, scaring Sheldon. Sheldon gets Leonard back by hiding in the apartment couch while Leonard is sitting on it talking to Priya. When Leonard is done, Sheldon pops out of the couch roaring, wearing a green shirt, purplish zombie makeup and fake blood on his lip. Sheldon: "Bazinga punk! Now we're even!"
Romantic False Lead: Some for Penny, some for Leonard — although his are more Little False Leads, in that he'd always prefer to be with Penny.
Romantic Spoonfeeding: In one scenario of the What If? episode, Raj and Howard share a dessert and Raj cleans Howard's mouth with a napkin. Howard is disturbed, but Raj is delighted ("That is so us!").
Roommate Com: Sheldon and Leonard are roommates and genius level physicists. They also hang out with fellow scientists and equally geeky and nerdy Howard and Raj. Penny, an attractive blonde, moves across the hall and becomes involved in their life. There are some elements of Work Com when the plot revolves around the guys' work or colleagues at Cal Tech university.
In-universe. Sheldon identifies with The Grinch ("I was right there with him all the way until he gave in to the Holiday Who Whooey at the end") and according to Leonard roots for the Sun against Frosty the Snowman ("A trivial piece of holiday flotsom in a stolen hat)".
Another episode reveals that Sheldon actually does root for the Empire.
Sheldon: Aside from their tendency to build Death Stars, I've always been an Empire man.
Ruined Forever: [invoked] In "The Raiders Minimization", Amy ruins Raiders of the Lost Ark for Sheldon by pointing out that Indiana Jones wasn't necessary for the story, that it would have had the same conclusion without him. Sheldon then tries to do the same to something beloved of Amy, like Little House on the Prairie.
The episode where Sheldon's World of Warcraft account got hacked - while the desperate lengths the foursome get into to try recovering his items (including going into a Black Market in Goldshire, of all places, and Raj volunteering to seduce someone for the information), but completely ignores what actually happens when a WoW account gets hacked, and the reasons for doing so.
And then another episode's scene where Raj had bought a very nice area rug at Big Lots, but ended up with eleven extra rugs because it was only available in a case of twelve. In reality, Big Lots only sells single rugs, and they're not available (in store) by the case.
When the girls went to Disneyland, they went to the Bibbidi-Bobbidi-Boutique and got dressed up like Disney Princesses. In reality, they actually don't do that to adults - but it wouldn't have been funny otherwise.
In "The Dumpling Paradox" the guys and Penny are playing Halo, but the sound effects don't match up with any of the Halo games, and several comments about mechanics that aren't present in Halo.
Sheldon knocking on a door, any door. Lampshaded when Penny opens the door after two, and then supplies the third herself. To which he responded, "That's just wrong."
When Sheldon saves Leonard from the rocket fuel explosion that destroyed the elevator.
Leonard: I'm just glad Sheldon didn't rat me out to the landlord... or the police... or Homeland Security...
Sheldon has a bad breakfast: orange juice - "In what universe is that non-pulp?", English muffin - "In what universe is that 'lightly toasted'?" and margarine - "Well, I have no difficulty believing you're not butter."
Rules Lawyer: Played straight with Sheldon, who exploits the Roommate Agreement for all it's worth. Then hilariously inverted when Leonard gets his own literal Rules Lawyer who then proceeds to exploit every technicality in the Agreement for all it's worth.
His idiosyncratic door knocking, three sets of three knocks, with the name of the person on the other side between each knock. And when he does it to Penny, her responses to such. Notable examples of this are when Penny turns it into a door knocking war (repeating his knocking pattern from the other side of the door and saying his name) and when Sheldon knocks as The Flash. Also when he's inside Amy's apartment, knocking while she's in the hall.
"I'm not crazy! My mother had me tested." and "Bazinga" (a coined term Sheldon made to identify when he is pranking someone.
"Coitus", originating with Howard in the pilot but often used by Sheldon as a substitution for the word "sex". Leslie Winkle used it frequently as well.
First confirming that what someone else said was a joke before giving a slight titter in response.
"That's my spot."
Soft Kitty is sung at least once a season and almost always interrupted; whoever's singing it always has to start from the top, not where they left off.
Sheldon making sure whoever's getting the Chinese food, usually Leonard, gets his order correct and all the correct sides and sauces and such, when they brings the food home. They never fail.
Sheldon: Did you remember to ask for the chicken with broccoli to be diced not shredded?
Sheldon: Even though the menu description specifies shredded?
Sheldon: Brown rice, not white?
Sheldon: Did you stop at the Korean grocery and get the good hot mustard?
Sheldon: Did you pick up the low sodium soy sauce from the market?
Sheldon: Thank you.
Leonard: Youíre welcome.
Sheldon getting Restraining orders as of season early season 7. He has restraining orders from Stan Lee Leonard Nimoy Carl Sagan and Bill Nye. Leonard makes a joke about him getting one from Stephen Hawking imagining if Howard arranged a meeting between the two.
Saying that it's a social convention to bring an upset person a hot beverage.
Sheldon frequently criticizes geology for "not being a real science," and he enjoys mocking geologists.
Lactose Intolerance and other dietary restrictions.
Declaring "Here we go..." (usually right before Sheldon goes on one of his rants)
Like Bernadette, Leonard is frequently the victim of jokes about his height.
Her general ignorance of most geeky pop culture, including Stan Lee and having never watched Raiders of the Lost Ark. This has been played down in later years; because of her close proximity to the guys, she has come to learn much of that stuff.
Penny's "check engine" light is constantly on, Sheldon and others bug her about attending to it, and she refuses.
Penny's use of the guys' wifi, and Sheldon changing the password to something like pennygetyourownwifi.
Leonard: No spaces.
Whenever she asks about something she doesn't understand, it's usually to Sheldon, and Leonard or Howard may try to stop her before groaning over having to hear Sheldon explaining something.
His knowledge and familiarity with more "girly" topics such as loving Bridget Jones' Diary and knowledge of fashion.
Not being able to talk to or around women without being drunk or influenced by other substances. Though he gets over this eventually.
He is constantly saying how he came from a poor background only to have Howard remind him his father is a gynecologist who drives a Bentley and in some cases brings up his house full of servants. Raj tends to downplay these
(on the Bentley) "It's a rental"
(on the servants) "two of them are children"
His lack of a Ph.D
His top-volume screaming matches with his mother.
His sex robot is brought up a few times
Her proximity to experiments involving dangerous bacteria like yellow fever and combining Ebola with the common cold.
"Not that we would ever admit to that, because that would be very bad."
Her inability to understand a joke (though it disappeared after a few episodes).
Her height (Melissa Rauch is just under 5').
Sounding just like Howard's mom when yelling or upset.
Childhood pranks being pulled on her.
Her infatuation with Penny, both as simply best friends and with some homosexual undertones. Also her finding Bernadette less attractive as well as pretty much considering Bernadette the third wheel in the in their group.
Using her harp to play songs that normally are not played on the harp (like TV theme songs or Bon Jovi)
For various characters:
The use of high-end scientific research equipment to perform everyday food prep tasks
According to President Siebert, this is how Sheldon maintains his position at the university. Siebert thinks Sheldon is "nuts" (not without reason - Sheldon once came knocking on his door at one in the morning, ruined a fundraiser, took his trousers off when being presented with the Chancellor's Award and dropped a huge quantity of foam on his head), but the "board insists he has a beautiful mind," so he stays. Interestingly, the Board seemingly still supports him even after aforementioned foam prank.
Sheldon's mother persuaded Gablehauser, the department head, to re-employ him on the one occasion he was sacked. If your boss fancies your mother, this helps too.
Bernadette notes that her father, being a cop, can help her out of speeding tickets.
Raj: I am talking to you?! *Shakes hand* Hello Penny! How are you?!
Self Induced Allergic Reaction: Howard eats a nut bar to stall Leonard so they could set up Leonard's surprise birthday party. And because Penny was going to hook him up with her easy girlfriends. This is after he fakes an allergic reaction to the same thing for the same cause, only to realize the group wouldn't have enough time. And well...
Serious Business: Amongst many other things (of which the weekly routine of meals and evening activities are just a small part), in the episode "The Hofstadter Isotope" a discussion about who would succeed Batman in the event of his death between Sheldon and an online community eventually leads to Penny's date being cut short after he is brought into the discussion as well.
World of Warcraft to Sheldon. When his account gets hacked he calls the FBI... and when they hang up on him he calls the regular police.
Sexy Shirt Switch: Penny in the third episode of the third season, after her and Leonard's first night in his apartment and she was dancing and making French toast.
She Cleans Up Nicely: The normally drab, dowdy and plain Amy F-F, when she goes oujt with the other girls and has the Disney Makeover, being made up and dressed to look like Snow White. She also stands up straight rather than adopting her usual hunch-shoulders stoop. The result is..... wow.
Raj because he doesn't want Leonard dating his sister.
Her parents because Leonard isn't Indian.
Amy, Bernadette and Penny want Leonard/Penny to happen/think Priya is out of line for trying to change Leonard and demanding he stop being friends with Penny.
Sheldon doesn't like her because she's mean to him and challenged the Roommate Agreement to help Leonard.
Ship Sinking: Amy is pretty much this to the popular Penny/Sheldon ship. In particular, "The Flaming Spittoon Acquisition" not only shows how serious Sheldon is about Amy, but even dedicates a scene to addressing why he is not compatible with Penny. Sheldon's speech even uses some of the most common elements for the ship that appear in just about every "Shenny" fanfic, which Penny then proceeds to tear down one by one. The ship isn't only just sunk, it never existed.
A later episode had the characters exploring What If? scenarios and had a scene where Penny was flirting with Sheldon, to the point of undressing to seduce him. While Amy does eventually inject her own feelings into the scenario, Sheldon stayed in character and was unfazed by Penny's actions.
Ship Tease: Played with between Leonard and Amy. Amy coerced Leonard to be her date for a co-workers wedding (Sheldon doesn't like going because There weren't any other scientists his age) and Amy ended up cheering Leonard out of a funk. To his own surprise he enjoyed spending time with her and gave her a kiss on the cheek for a goodbye, with Amy misinterpreting it as being that Leonard had fallen for her. Of course, the kiss on the cheek was part of the commercials for the episode.
Again in Season 5 when Sheldon asks Penny on a date to make Amy jealous when she begins to date Stuart.
Shot to the Heart: Sheldon tries to prank Howard with an Electric Joy Buzzer, but Howard appears to collapse from a heart attack and is instructed to stab a syringe of adrenaline straight through his heart. Of course, it all turns out to be a counter-prank.
A more subtle example: Leonard, Sheldon and Penny watch an anime called "Oshikuro the Demon Samurai". That was an allusion to an episode of Two and a Half Men, in which the animated adaptation of "Oshikuro" (which was a comic book then) was being made, and Charlie had to compose the opening song.
When Sheldon won a prestigious award and was nervous about giving an acceptance speech. He took a few drinks to calm his nerves, overshot the mark, and one of his hijinx was singing the periodic table of elements to much the same tune as Tom Lehrer. Actually it's a shout out to Gilbert and Sullivan as the tune he was singing to was "A Very Model of a Modern Major-General." Which is the same tune.
Mega nerd Wil Wheaton wore a Fruit Fucker T-shirt when he appeared on this mega nerd show. For those who don't know, Wheaton's a homeboy of the PA crew, to the point of playing in several D&D campaigns with them, and is subsequently ridiculed mercilessly for his choice of character name.
When the four come back from their Arctic expedition, Leonard, Howard, and Raj all have grown caveman-like hair and beards, while Sheldon has a perfectly-groomed goatee... just like the one alternate-universe Spock had.
Sheldon's various superhero T-shirts.
Sheldon named their bowling team "The Wesley Crushers" meaning that they would crush Wil Wheaton. Everyone else (including Wheaton) saw it as a Fan Shout Out to the actor.
In the episode guest starring Stan Lee, the judge who throws Sheldon in jail is named "J. Kirby".
There are several shout outs to Battlestar Galactica. They range from the characters talking about watching the show to Leonard, as Howard puts it, "taking out his aggressions on innocent Cylons" (i.e. he destroys a Cylon action figure with a laser).
Many shout outs to Star Trek both old school and new school. Penny gives Star Trek figurines to the guys, Sheldon is at first upset that he missed the Star Trek reboot then upset that he didn't get a Leonard Nimoy Spock standee, a quick Lt M'ress mention, Sheldon's feud with Wil Weaton, Sheldon compares their friends to a landing party ("Now we have a Dr. McCoy!"), and of course...."Do you know what this means? I possess the DNA of Leonard Nimoy!!!"
There was an ironic shout-out to Firefly by Joss Whedon in "The Staircase Implementation":
Sheldon: "Roommates agree that Friday nights shall be reserved for watching Joss Whedon's brilliant new series, Firefly."
Leonard: "Does that really need to be in the agreement?"
Sheldon: "Well we might as well settle it now, it's gonna be on for years."
Sheldon's journal in "The Bozeman Reaction" is a shout-out to Rorschach's Journal in Watchmen.
Sheldon: Sheldonís journal. Security system in place. However, sleep continues to elude me. Iíve seen the underbelly of Pasadena, this so-called City of Roses, and it haunts me. Ah, the injustice, I lie here awake, tormented, while out there evil lurks, probably playing ''Donkey Kong'' on my classic Nintendo.
Strangely enough, there is no mention in that episode that Bozeman, Montana where Sheldon decides to move to was also the location in Star Trek: First Contact where humanity made first contact with the Vulcans. You'd think Sheldon of all people would have brought that up.
Sheldon's frequent quoting from the extremely detailed Housemate Agreement, right down to paragraphs, sections and subsections, evokes Rimmer's obsession with the Space Corps Directives on RedDwarf. As sci-fi nerds, of course Sheldon and the rest - and certainly the show's creators - would be aware of Red Dwarf. Sheldon as a more pernickity Rimmer makes great sense, too, with the rest of the cast taking it in turns to play the Lister role.
In fact, Sheldon owns all sixty-one released episodes of the BBC series "Red Dwarf", as revealed in "the Friendship Contraction".
This would include the original eight seasons (52), the three-part "Back To Earth" and the six episodes of Red Dwarf X. Although the creators were sufficiently on the pulse to know that Red Dwarf X was being made, The Friendship Contraction was broadcast approximately eight months before the new season of Red Dwarf was initially broadcast in the UK.
And... the whole idea of Howard going up into space as the world's least likely and most temperamentally unsuited astronaut. Everybody, including university benefactor Mrs Latham, makes dismissive remarks about his being a "space plumber". Howard soon finds out he's only there to do the equivalent of servicing the chicken-soup dispensers. His quirks make him the butt of the joke from more macho astronauts. While entranced with the view at first, he soon comes to regard it as excruciatingly dull. DoesThisRemindYouOfAnything?
And in the one where Howard gets into an embarrassing situation with a robot arm, he programs the arm to respond to a snarky Sheldon comment, by having it turn to him and jerkily, but very obviously, making a finger-gesture. This is not the American middle finger, but the British V-Sign with two fingers. Compare the skutter (maintainence robot) in Red Dwarf who makes a similar derisive gesture to Arnold Rimmer after being provoked by a similar superior sneer.
In The Holographic Excitation, there is a blatant shout-out to Sir Terry Pratchett's Discworld books. Specifically, the The Science of Discworld series, co-authored with prominent British scientists, in which Pratchett's fantasy world is used to mirror and illustrate developing scientific thought. In the books, the wizards of Unseen University (among them a rather nerdy type with glasses who affects a big baggy parka) accidentally create a bizarre pocket universe centred on a spherical world which orbits its sun. Stuck for what to do with it, it ends up gathering dust inside a protective glass sphere on somebody's desk. Meanwhile a geeky glasses-wearing scientist in a parka fires up holograms of Earth, planets and solar system to please his girlfriend. Leonard speculates that everything might just be one giant information-gathering hologram, being read by intelligences an unguessable distance away...
The creation of the pocket universe in the Discworld - including Planet Earth - was done with the specific intention of averting a seriously Big Bang, by diverting a lot of dangerously destructive energy down a harmless path...
Bernadette proving to Howard that she can fake realistic laughter at his jokes is a pretty clear reference to the fake orgasm scene in When Harry Met Sally.
Shower Of Love: Leonard and Priya have sex in the shower in "The Agreement Dissection".
Shown Their Work: The show goes well out of its way to get the details of the science and tech stuff right, as well as generally listing actual things that geeks are into like Halo and Battlestar Galactica. Not only that, they have an actual physicist, Dr. David Salzberg, on hand to fill in the correct dialogue and write appropriate diagrams and formulas on the white boards. In fact, almost any mention of high-level science, such as theoretical procedures in which the characters would either be versed or have read/heard about through peer-reviewed journals are written as Science To Come (or similar) in the script, awaiting Salzburg's insight in order to be replaced with something relevant and accurate. All of this leads to Genius Bonus. This includes:
Sheldon's search for magnetic monopoles in the second season finale was based on actual research being done at the time, with results posted over the season break. Similarly, his dilemma figuring out the contradiction with particles moving through a graphene sheet was related to contemporary research that later won the Nobel Prize.
Rivalries between different scientific specialties is also on the nose, with the show focusing much of it with Sheldon (Theoretical Physics) vs Leonard (Experimental Physics), Raj (Astrophysics) and especially Howard (Engineering, no Ph.D). Sheldon also holds a particular disdain for Geologists.
Comparatively recent events in geekdom including a conversation involving the meaning of Final Crisis, shake-ups in the Batman comics run and the re-establishment of the DC ComicsMultiverse.
Penny, whilst in a comic-book shop, surrounded by nerds: "What's a 'multiverse'?" Sheldon: [turns to Leonard] "Get her out of here."
In "The Thespian Catalyst" Penny tries to teach Sheldon about acting and eventually gets to improv. Sheldon kept going off on tangents (asking for frozen yogurt at a shoe store) and Penny was rolling with it, which only confused Sheldon because (obviously) there is no such thing as a shoe warehouse/frozen yogurt hybrid store. Penny then explained the number one rule of improv, you say "Yes" and accept all scenarios given.
Howard's adventures in space involved a couple of locations for the International Space Station and the Module used for travel. They actually had Mike Massimino from NASA as a consultant and guest star and he helped them build the sets to the approximate scale and look.
Sibling Yin-Yang: Sheldon's fraternal twin sister, Missy. In "The Luminous Fish Effect", after talking about what a pain Sheldon is, Sheldon's mother tells Howard that God didn't give her more than she could handle; she has two others kids who are "dumb as soup."
More specifically, while Sheldon is a theoretical physicist, his twin sister Missy is a hostess at Fuddruckers.
Silent Whisper: Raj Koothrappali does this into Howard's ear every time he wants to talk but there's a woman in the room and he's not drunk. Howard translates. No longer the case in Season 7 when Raj has developed enough to speak before women without needing a drink.
Barry Kripke, Wil Wheaton and Leslie Winkle at different points, all for Sheldon.
Arthur 'Professor Proton' Jefferies hates Bill Nye the Science Guy mainly because he thinks the man stole his show.
Significant Reference Date: In the episode entitled "The Excelsior Acquisition", Sheldon finds a traffic summons conserning an traffic incident that occured on 11/16, the airdate of "The Adhesive Duck Deficiency" in which the violation happenend.
In "The Agreement Dissection" Sheldon notes that Leonard violated the Roommate Agreement on April 28th, same date as the original broadcast date.
A Simple Plan: Played with in "The Loobenfeld Decay." The lie works fine, but Sheldon is convinced it'll fall apart, and keeps trying to overcomplicate it.
Single-Target Sexuality: Amy's early insistence that she has no interest in romantic love or physical contact ("up to and including coitus") takes on difference shades when she very openly admires Penny's "secondary sexual characteristics" and even suggests "harmless lesbian experimentation" at a sleepover. That said, she never shows any interest in any woman other than Penny.
And as typical for this show, it's a perfect recreation of "KHAN!" and not the osmosis version. Sheldon doesn't look up at the sky, he looks straight ahead with a close-up and screams "WHEATON!" and then the camera cuts to an Astronomic Zoom pulling away from Earth.
Small Reference Pools: Usually very good at averting this, although it sometimes sacrifices realistic characterization for (comparatively) more familiar references, like the time Sheldon said Ubuntu was his favorite Linux distribution.
Notably, no self-respecting nerd would be caught dead playing Monopoly when there are so many wonderful obscure German games about trading. Settlers of Catan, for example, which is beginning to extend it's reference pool somewhat.
And of course, there was the questionnaire that Sheldon made for Raj, Howard and Leonard:
Sheldon: [to Raj] How could you think my favorite amino acid was glutamine?
Slow Loading Internet Image: A video variation. Leonard and Priya are communicating through teleconferencing and are attempting to have a long-distance intimate date. Leonard takes off his clothes, but when Priya starts to take off hers, the signal freezes just as she's taking off her bra.
The Smurfette Principle: The show started with five main characters: the four male nerds, and The Chick who lives across the hall. However, in seasons 1 and 2, there was often Leslie Winkle acting as a female Sixth Ranger. And later the show got eve more females, with Bernadette and Amy both being upgraded to main cast status for all the episodes they appear in. Raj's sister Priya was also a major character, and mothers of the main characters are frequently involved.
Prime example in "The Cooper-Hofstadter Polarization" where Sheldon tries to make Leonard's head explode a la Scanners. Later, Penny finds a picture of herself on Wolowitz's website (listing her as his girlfriend) and does it to him.
Leonard has shades of it as well, especially when dealing when Sheldon.
So Unfunny It's Funny: Many of Sheldon's jokes come across this way, usually because it is only mildly amusing but not nearly as funny as he finds it. One in particular involved a pun Amy made about ethanol ether vs. "either," and Sheldon felt he had to explain why it was funny.
Sheldon: *after being outvoted* I never get my way.
Leonard: *dumbfounded* You always get your way!
Sheldon: *beat, thinks about it* I'll stipulate to that if you give me my way.
In fact, Sheldon's entire strategy in life is to whine and pitch a bitch fit until everyone gives him what he wants in exchange for some peace. Rule of Funny is the only reason they haven't pinned him down and cut out his tongue.
Stalker with a Crush: Ramona in "The Cooper-Nowitzki Theorem", who is more in love with Sheldon's mind than him.
Standardized Sitcom Housing: On the whole the show uses the typical set-up, with the hallway between apartments used extensively for scenes and conversations. But there are moments where they get camera angles showing the "fourth wall" with a completed set, one being a POV of Sheldon coming in from the hallway when the others were staging an intervention on his refusal to get a driver's license.
The show manages a fairly clever recycling of the set by using the center hallway to represent three different floors with a minor redress, allowing a Walk and Talk with only one set.
When Amy buys Penny a portrait of the two of them that is too garish to display and too expensive to get rid of, the matter is eventually resolved when Penny hangs the portrait on the fourth wall of her apartment. The hanging is portrayed by the camera shot representing the "point of view" of the portrait being straightened when hung.
Status Quo Is God: Lampshaded by Sheldon. After Amy kisses him while drunk, he suggests they treat their relationship like a malfunctioning computer and restore it to the last point they both agree that it worked (which, given that this is Sheldon we're talking about, is quite a mature thing to suggest).
Stupid Question Bait: Sheldon opens up to audience questions as a way of getting everyone back on topic after the group's panel on the ethical use of science in the 21st century turned into everyone squabbling as the panel consists entirely of friends and couples. Unfortunately, the person in that audience to respond was their friend Penny, who only wanted to add additional commentary to the squabbling. It was probably his fault for not prefacing it with "questions that actually have something to do with ethics, and not our personal problems".
Early season one Penny started dating a guy for the first time and Leonard was a little miffed about it. When the others pressed him they asked "Is it because he looks better than you?" and Leonard admitted that it was true, "He was rather dreamy."
Surprise Party: In one installment, Penny tries to throw Leonard a surprise birthday party when she finds out that he's never had a birthday party, but it doesn't work out. Leonard has to take Howard to the emergency room for a peanut allergy reaction and they don't get back home until well after the party is over.
Surrounded by Idiots: Despite being surrounded by geniuses, Penny has common sense that none of the others possess.
This forms a lot of Sheldon's frustrations towards Penny, which gets reversed in "The Shiny Trinket Manuever" where Sheldon keeps getting distracted at a jewelry store;
"Congratulations for your award, Sheldon! I have brought you a cake from the restaurant. To celebrate, not because someone has sneezed at it..."
The episode "The Griffin Equivalency" shows Raj answering his parents video chat with, "Hello mommy and daddy, good to see you. I'm not drunk."
Sheldon defends his mental status with this gem: "I'm not insane. My mother had me tested."
In the episode "The Spaghetti Catalyst", Sheldon is told that he cannot hang out with Penny since she's Leonards ex. Trying to hide the fact that he has already made dinner plans with her, he sits down to eat with the guys. When asked if he wants the last dumpling, he thus says: "Certainly. It's not like I have to moderate my food intake because I'm planning on eating again very shortly."
In "The Desperation Emanation", Bernadette brings up a pact she made with her coworkers after a petri dish of genetically modified super-virus went missing.
Bernadette: That day we made a pinky swear never to admit we crossed Ebola with the common cold. Howard: Why the hell would you cross Ebola with the common cold? Bernadette: We never did. That would be a terrible, terrible thing.
Stuart when he talks to a cute woman dressed as a Hot Witch at his and Raj's Halloween party. She compliments their monster food as it looks fun.
Stuart: I like to think of fun things like that. Because I'm fun. I'm not clinically depressed at all.
Swapped Roles: Whenever Sheldon orders food, he gives Leonard a Long List of strict requirements for his order. In "The Einstein Approximation," Sheldon kinda sorta gets a job at the Cheesecake Factory, so Leonard is the one giving him the food order for a change. Leonard really enjoys this:
Leonard: Hang on. Black beans, not pinto beans?
Leonard: Double guacamole?
Sheldon: Of course.
Leonard: No cilantro?
Leonard: Lettuce shredded, not chopped?
Leonard: You understand why Iím doing this to you?
Sheldon: I do.
Leonard: Thatíll be all. (to Raj and Howard) That was fun.