A Good, Old-Fashioned Paint Watching: In "The Clean Room Infiltration," Amy organizes a traditional Victorian Christmas party. For entertainment there are Parlor Games dating to this period. The first seen involves blowing a ball of wool across a table. Penny and Dr. V. M. Koothrappali play along. But by their reactions, they find this game extremely boring.
Above the Influence: Leonard in "The Middle-Earth Paradigm." After a brief confrontation between Leonard and Penny's ex at her Halloween party, Penny visits Leonard in his apartment a little drunk and upset over what happened. Leonard ends up comforting her and she starts kissing him. While obviously enjoying it, he pulls away:
Leonard: Does the fact that you've been drinking and that you're angry at Kurt have anything to do with this? Penny: It... might. (sigh) Wow, you are really smart! Leonard:Yeah, I'm a FREAKING genius. Penny: You are so great, why aren't all men like you? Leonard: Because if all men were like me, the human race wouldn't survive!
Subverted in the third season finale where a drunken Penny takes Leonard to bed, though he did genuinely mistake it for a desire to get back together and was upset when that wasn't the case.
In "The Hesitation Ramification" Penny is drunk and depressed because her part in a TV episode gets cut and she proposes to Leonard. He turns her down but questions himself later.
Absent Animal Companion: Amy Farrah Fowler has a smoking pet monkey in one episode that is never mentioned again afterwards. Fowler is actually forced by her academic superiors to relinquish the monkeys she keeps at home. Not because of the smoking or the unauthorised taking her work home with her, but for "unprofessional behaviour": when monkeys crazed by nicotine deprivation started flinging excrement at her in protest, she threw it right back.
Accidental Hero: Sheldon on multiple occasions. He really liked Leonard's girlfriend mid-Season 2, Dr. Stephanie, and thus worked extra hard to try and make their relationship work. It got to the point he hacked Leonard's Facebook profile and sent a relationship request; when Leonard found out, he was furious, although it turned out okay when Stephanie confirmed the request. When Leonard and Penny broke up late Season 3, it was his antics trying to be with both Penny and Leonard that ended up getting the two back to being friends.
Then there was the time he unintentionally sabotaged Leonard's relationship with an Asian co-worker. As it happened, she turned out to be a North Korean spy trying to exploit Leonard's national security clearance. Sheldon drove her away before Leonard revealed anything really important.
Leonard's first day in the apartment. Sheldon saves his life by sacrificing the elevator when the rocket fuel experiment goes awry.
Accidental Kiss: When a drunk Rajesh attempts to kiss Bernadette, Howard gives a Big "NO!" and interposes himself between the two. And he doesn't kiss his girlfriend.
Accidental Pervert: In "The Mommy Observation", the gang appear in one of Raj's murder mystery dinners. Stuart is playing the corpse, lying on the floor. At one point Bernadette stands right next to him. His gaze goes up and he mentions: "I can kind of see up your skirt."
Acquired Situational Narcissism: Rajesh, episode "The Griffin Equivalency." At the least, he is drunk throughout most of the episode, and when drunk, he tends to be somewhat insufferable regardless of the situation.
Howard claims he's insufferable even when he's not drunk, but because of his selective mutism, Penny just doesn't hear it.
In Season 1, Episode 3, "The Fuzzyboots Corollary," Leonard says that if anyone asks why Sheldon cancelled, Sheldon had a chicken carbonera sub at Quizno's for lunch. Jim Parsons gained internet infamy for his squicky appearance in the "Hungry Like the Wolf" Quiznos commercials.
In one episode, Kaley Cuoco's character Penny is talking about an upcoming play and says, "This could be my only chance to play Anne Frank." In 8 Simple Rules, Kaley Cuoco's character Bridget was Anne Frank in her school play.
Penny later got a commercial gig that showed her riding horses. Kaley is an avid rider, and in fact broke her leg the previous season after she fell and the horse trotted over it.
Courtney Ford showed up as a geeky girl and made a reference to Superman. Ford is not only quite geeky herself, but is married to Brandon Routh of Superman Returns.
In an early episode, the boys consider recruiting "TV's Blossom" (Mayim Bialik) to their Physics Bowl team, as Raj has heard she has a Ph.D. in "neuroscience or something." Dr. Bialik does, in fact, have a Ph.D. in neuroscience, and later appeared on the show as Amy Farrah Fowler, a neurobiologist. After the Bialik suggestion gets shot down, he then suggests "that girl from The Wonder Years" and Danica McKeller later had a guest spot as Abby, one of the girls Sheldon meets and are impressed by his Green Lantern's limited edition Lantern.
Sara Gilbert appears throughout the series as Leslie Winkle, a sort of friend-with-benefits for Leonard. She and Johnny Galecki (Leonard) played supporting roles on Roseanne, in which they played a couple (eventually married) with essentially the same dynamics of passive guy/sarcastic dominating girl. Amusingly, Chuck Lorre previously worked on Roseanne as a writer and producer.
Sheldon makes reference to the theme to Teenage Mutant Ninja Turtles (1987) as being his favorite tv theme song. A lesser known fact of creator Chuck Lorre is that he used to be a music composer for kids shows before he got into sitcom writing, and one of his songs actually was that theme.
Teller plays Amy's father in "The Bow Tie Asymmetry", and throughout the episode, Amy's mom keeps preventing him from speaking, until they're gathered for Sheldon and Amy's wedding, when he says "Thank you" to Penny for telling off his wife.
In The Space Probe Disintegration, when Raj goes off on a rant at the elderly Indian man who dents his car in the ashram carpark, the old man in the car looks oddly familiar: he has been identified as an actor who played Mahatma Gandhi in an Indian TV adaptation of Gandhi's life, and does indeed bear a very strong resemblence.
In "The D&D Vortex", Penny takes a liking to William Shatner. Shatner and Kaley Cuoco appeared together on multiple commercials for Priceline.
In one episode Leonard mentions how he might end up half-eaten by crabs in the trunk of a car. This is exactly what happens to Johnny Galecki's character in I Know What You Did Last Summer.
Actually Pretty Funny: Sheldon almost never laughs out loud, usually managing an idiosyncratic snicker at something that might amuse him or maybe a guffaw at one of his own jokes. But one of the more silly jokes on the show involved an extended scene with Penny mocking Leonard with a "stupid" voice (for thinking her history paper was going to fail when she actually got a B-) and then we cut to Sheldon, laughing hysterically because "That's exactly what you sound like!"
Raj's speaker shirt in "The Excelsior Acquisition" has been annoying others throughout the episode, but when Sheldon finds out about a ticket for running a red light:
Sheldon: I'm not going to pay a fine, that would imply I'm guilty.
When Kripke fills Sheldon's office with helium while the latter is doing an NPR interview, the entire cafeteria laughs their ass off, including Leonard, Howard, and Raj.
Sheldon: You laughed?
Leonard: I fell to the floor.
Adam Westing: A lot of the guest stars that play themselves are this.
Wil Wheaton is an Unknown Rival to Sheldon at first, and plays up being a jerkass celebrity. Part of the joke is that Sheldon actually LOVED Wesley Crusher, while many fans did not, but hated Wheaton for a missed convention in his youth.
Levar Burton pops up as kind of a mooch, easily showing up at fans' requests with the promise of food and gas money.
Stephen Hawking ends up befriending the group but proving to have a prankster side, he really enjoys trolling people online. "When you spend all your time in a wheelchair, you want to mix things up a bit."
James Earl Jones shows up milking his role as Darth Vader, not missing an opportunity to hang out with a fan which includes riding a ferris wheel, going to a strip club, going to a sauna and door bell ditching Carrie Fisher's house. Fisher herself is mentioned to be crazy, and shows up with a baseball bat.
James Earl Jones: Let me guess... You love Star Wars.
Leonard ends up recruiting the trope namer Adam West to come to Sheldon's birthday party, playing up the has-been actor talking about the glory days of being Batman.
A Date with Rosie Palms: During "The Werewolf Transformation", Amy imagines a long-haired, shirtless Sheldon riding a horse, then leaves to "brush her teeth".
Advertising Campaigns: To promote the Season 4 move from Monday to Thursday nights, the gang is seen sitting around eating food when Sheldon announces that he invented a transporter to help them move from Monday to Thursday. Everyone 'beams out' of their chairs then 'beam back in' in the exact same positions. Leonard notes that it doesn't feel very different, while Howard complains that his food is now cold.
In 2011, American cable channel TBS bought the rights to air The Big Bang Theory and advertised it by showing a clip from Family Guy of Peter jumping into midair and getting frozen there. After he says "Call a Scientist!", we cut to a clip from Big Bang of Leonard answering the phone. Oddly enough, the footage of Peter came from an episode which only five minutes earlier had featured a Big Bang parody, complete with stars Jim Parsons and Johnny Galecki voicing their characters.
Advice Backfire: Inverted — When Stuart is about to go on a date with Penny, Leonard deliberately gives Stuart what he thinks is bad advice about what to do on the date. Stuart follows the advice and ends up making out with Penny anyhow. Penny called out Leonard's name rather than Stuart's, though, and since the advice was exactly what Leonard had done himself, the implication is that Penny was simply trying to replace Leonard with someone very similar.
Multiple, multiple episodes have Sheldon being called out on how much of a jerk he is and learning not to be such a jerk. Then in the next episode he's right back to being a jerk.
"The Space Probe Disintegration" has Sheldon calling out Leonard for his hypocritical attitude and how mean he is to Sheldon much of the time. Leonard says that he's sorry... and then goes right back to being a jerk to Sheldon in the episodes after that.
"The Champagne Reflection" has Bernadette realizing how much of a jerk she is and feeling awful about it. After this episode she goes right back to being a jerk.
"The Maternal Combustion" has Beverly realising that there is more than one way to raise a child and she promises that from now on she will shower Leonard with unconditional love. After this episode, she is back to being a jerk in most appearances until "The Maternal Conclusion" where she and Leonard make amends when he forgives her.
A Fool for a Client: Sheldon represents himself when he receives a ticket for running a red light. He loses.
Afraid of Needles: Leonard is so afraid of having to get stitches for his hand that he vomits — and when Howard sees them, he nearly does as well.
Sheldon: You know, Germans have an interesting pre-wedding custom—
Howard: Then it probably isn't for me!
Well, more to do with the fact that Howard's family fled from Europe during the War and included Holocaust survivors. Not to mention that Amy's reaction to the news that Bernadette's family were once their neighbors in the same village, subtly implying that they might have sold them out.
Also subtly invoked in a TBS commercial for the show, as part of the "What does TBS stand for?" series of ads:
Sheldon: It stands for "Text Bau Steine."
(Scene switches to episode clip)
Sheldon: The Germans have always been a very comforting people.
(Ad cuts to Howard giving the camera a "Really?!" sort of look)
All Girls Want Bad Boys: Penny seems to be attracted to muscular and obnoxious guys (Kurt from the pilot episode and the unseen boyfriend of the first season finale) and subsequently hates herself for it. One of the main reasons she gives Leonard a chance is that he was so far removed from the previous guys she would date.
Inverted in "The Flaming Spittoon Acquisition" with Sheldon, Amy, and Stuart. Stuart asks Leonard about Sheldon and Amy and, after being told that they're not dating, asks Amy out. Stuart and Amy go on two dates before Sheldon charges back and asks Amy point-blank to be his girlfriend.
''The Barkersfield Expedition" has Amy declare that she likes bad boys, prompting Penny to snark back "as evidenced by your boyfriend and his fear of hamsters..."
All Just a Dream: The majority of "The Recombination Hypothesis" consisted of Leonard daydreaming/wargaming a date with Penny.
All Take and No Give: Sheldon has this relationship with pretty much everyone the Roommate/Relationship agreements require Leonard and Amy to do a ridiculous amount of things for him while his contributions is to go from completely unbearable to just barely. The moment Leonard was able to make the agreement to work for him Sheldon changed it to make sure something like that never happens again.
It came to a head with Amy in The Spoiler Alert Segmentation where after telling her that he didnt want her to move in with him Amy exploded at him saying she is tired of waiting on him hand and foot while getting nothing in return and demanded to know why. Knowing he didnt have a leg to stand on Sheldon blamed Penny.
Coincidentally, this is also how Sheldon sees his friendship with Penny. She comes over and eats dinner practically every night without paying for it and without a formal invitation, and she hardly ever gives anything of equal value in return, at least in Sheldon's opinion (fashion and dating advice clearly don't have the same value as Chinese take-out to Sheldon until he meets Amy).
All Women Love Shoes: Penny, many examples. She even has Sheldon write her a "shoe-scanner app" for her phone, just so she can find the cheapest price on any pair of shoes she sees just by taking a photo of them!
Almighty Janitor: The janitor in "The Bat Jar Conjecture" solves the final question in a physics quiz competition after a casual glance. Made especially hilarious by the rest of the cast being unable to even identify it.
Janitor: Here, I am janitor. In former Soviet Union, I am physicist. Lenigrad Polyteknika. *Beat* Go Polar Bears!
Leonard and Penny spend a season engaged but putting off any real plans on getting married. When Sheldon calls them out on it, Penny suggests Viva Las Vegas! to Leonard and they get married later that night. A season later, after realizing that Beverly Hofstader is actually upset not getting to see them get married, they hold a second wedding where their family got to attend.
Sheldon and Amy get engaged but struggle with collaborating with wedding details (Amy wants a rustic Little House on the Prairie style carriage ride, Sheldon wants her to arrive at an honor guard of Stormtroopers). They decide to do a quick marriage at the court house, but Sheldon backs off as he realizes he wants a big wedding because he never thought he would meet someone like Amy and actually want to get married.
Howard's mother is featured most prominently. She's loud, over-bearing and treats Howard like a little boy.
Penny's dad. He constantly tells Leonard about Penny's previous boyfriends, though in his case, it's more about trying to convince Penny about how Leonard is so much better for her.
Leonard's mother is a cold, icy woman who belittles him and tells everyone how she treated her son like a scientific experiment.
Ambiguous Disorder: Sheldon. Leonard's mother Beverly. Amy. They all have something going on, being exaggerated versions of every geek and aloof-genius stereotype you've ever heard of. This leads to a good amount of fan speculation that one or all have Asperger Syndrome in some form. Jim Parsons has also stated that Sheldon "could not have more symptoms of Asperger's" but also stated the writers have not done it intentionally and he hasn't played Sheldon that way.
Raj. His sister even admitted that his family was wondering that about him. But besides some awkward moments both in the show and spoken of in passing, it's made pretty clear that he isn't gay... through a series of daydreams about his attraction to Bernadette. "Dance number aside, I am SO not gay." So he may be more Camp Straight. There was that time Leonard's psychiatrist mother described Raj and Howard as being in "an ersatz homosexual relationship". In the episode before he daydreams about Bernadette, however...
Amy has all but stated she has a big crush on Penny (and has admired both Bernadette and Priya as well), but could be interpreted as a Stupid Sexy Flanders in that she appreciates her own gender but is otherwise straight.
Sheldon (to Amy regarding letting Penny cut his hair): Amy, what do you think? Amy: There's not a hair on my body I wouldn't let this woman trim.
Penny casually refers to the fact her high school PE teacher had a crush on her and that they went to a Melissa Etheridge concert together. She does not disclose if she exchanged sex for grades, but offhandedly says it all worked out OK.
This scenario recurs in "The Big Bear Precipitation", when Penny secures a colleague's country lodge for the weekend, Leonard assumes the colleague is hitting on her and is male. Penny corrects the gender and casually remarks the price to be paid is her going to a Indigo Girls concert with the female doctor.
Amicable Exes: Penny and Leonard after their break-up. This of course causes friction when Leonard gets with Priya.
Ambiguously Jewish: Leonard. Who expresses an interest when Raj buys lobsters and prawns online for a post-Lucy binge-out.
There is sort of a Running Gag of the characters getting hit in the face and getting black eyes in the process. Admittedly, they try to avoid the Double Standard and Penny is sometimes hurt on a similar level.
Sheldon learning the hard way that one should not play bongos while walking down the stairs.
"The Locomotion Interruption": Penny is nervous about her job interview arranged by her friend Bernadette. Bernie lists Penny's personality traits, trying to convince her she's gonna be fine.
Penny: I havent been on a job interview in years. Im really nervous. Bernadette: Dont be. You are built for pharmaceutical sales. Youre cute, youre flirty and I started that like there were gonna be three things.
In "The Sibling Realignment", Leonard tries to list things Sheldon and his brother George have in common.
Leonard: I... I know you two have your differences. George: You mean pretty much everything about us? Leonard: Well, not everything. You're both tall, you have the same last name. Maybe I shouldn't have started this like it was a list.
Anachronism Stew: In-universe at a Renaissance Faire the main characters attend, with historical inaccuracies discussed by Sheldon. Later, Sheldon invents Three Person Chess and adds several new pieces and rules to the game, the result being that the medieval-styled classical chess pieces can now move using golf carts, time machines, transporter pads, and jetpacks.
After discussing the inaccuracies of the Renaissance Faire, the next time they visit at the end of the episode, Sheldon goes dressed as a Star Trek science officer, sporting a Tricorder and everything, recording the Anachronisms.
In a flashback to when Leonard moved in with Sheldon, set in 2003, he, Howard and Raj are dressed like it's The '80s. Or rather, a parody version of The '80s.
A variation in that the analogy was horrible to begin with. Howard tried taking Leonard to a bar to teach him how to pick up women, only to fail miserably. Howard tries to shrug it off as he is normally doing it alone and Leonard is cramping his style.
Howard: I'm a falcon who hunts better solo. Leonard: Fine, I'll sit here, you take flight and hunt. Howard: Don't be ridiculous, you can't just tell a falcon when to hunt. Leonard: ...Actually, you can. There's a whole sport built around it. Falconry. Howard: ...Shut up.
Raj's attempt to convince Leonard to ditch his current girlfriend (Raj's sister) for an evening in order to retrieve Sheldon's stolen World of Warcraft account:
Raj: Bros before... my sister.
And Zoidberg: Usually done by Sheldon with Howard, the only one of the guys without a doctorate. Invoked verbatim in S 4 E 11:
Sheldon (talking about Penny): "And then, one day, she meets a group of geniuses, and their friend Howard."
Angrish: Somewhere between this and Metaphorgotten, Penny got really angry at Leonard checking out a history paper she wrote and rewriting it for her, trying to calm her down with an analogy of "The shoemaker and the elves." After storming out, she came back in and tried screaming at him with her own analogy and got halfway through the "Feed a man a fish" story before giving up and just calling him an ass.
Anything That Moves: The physicist Dr. Plimpton that Sheldon invites over, sleeps with Leonard, Raj, and tries to seduce Howard, who has trouble being naked in front of Raj, all within a 24 hour period.
Raj wants Howard to tell his new deaf love interest that he has a deep sexy voice like James Earl Jones, not realizing she wouldn't know the appeal anyway.
Bernadette and Howard are dog-sitting for Raj and they lose the dog. While out searching for it, they decide they should call the dog's name using Raj's accent, leading to this Ho Yay-packed exchange:
Howard: When this all blows over, remember that voice. Its kind of a turn-on.
Bernadette: It turns you on when I sound like Raj?
Howard has mentioned that he finds Bernadette's voice sexy when she shouts in the same tone as his mother.
Armor-Piercing Question: In a girl's night out when they ended up playing "Truth or Dare", Bernadette asked Penny why she hung out and talked with Leonard so much even though she broke up with him. Penny replied that he was a great guy but felt he got too serious, which led to another question that what if she wanted him back and he was taken by someone else because he is a "great guy?" Penny didn't know how to respond to that and declared the game over.
Sheldon delivers a brutal one to Penny when she offers to give him advice about dating when she is chaperoning him to his first date with Amy:
Penny: My point, is that if you were as smart as you think you are, you would listen to me, since I know more about dating than you.
Sheldon: If you know so much about dating, how come I have a date tonight and you have nothing better to do than drive me to it?
Penny: *long, stunned silence* Fair point.
Sheldon in the Season 6 finale is trying everything he could to convince Leonard not to take a job working on a Stephen Hawking project on a boat. After various attempts with seafaring disaster statistics and general fear of sharks, Leonard tells him to stop it. Sheldon then points out Leonard and Penny are in a really good place right now and him leaving for 3-4 months could affect that, which obviously hit Leonard hard.
Sheldon's assessment of Hawaii: "a former leper colony on top of an active volcano where the disappointing ending to Lost was filmed."
Raj explains why he's stressed out in "The Space Probe Disintegration":
Raj: A space probe might be destroyed, my parents are going through an awful divorce, the guy who cuts my dogs hair just gave her bangs! (to Howard) You saw her. She looks like Jim Carrey from Dumb and Dumber.
Sheldon names things that people can become addicted to after one use: Crack cocaine, nicotine, Pringles.
In the series penultimate episode Amy and Sheldon are awarded the Nobel Prize in physics for their discovery of superasymetry earlier in the season. The Nobel Prize in physics is only given to people whose discovery has stood the test of time, meaning 20 years or more need to have gone by after a discovery is made. Sheldon and Amy simply arent eligible and wont be until the year 2039.
The theme song, performed by Barenaked Ladies, contains the line "the autotrophs began to drool". Autotrophs are organisms that sustain themselves by refining sunlight into energy, colloquially known as "plants", which are not generally noted for their capacity to drool. The appropriate term would be "heterotrophs", which refers to any organism that does not get energy directly from sunlight.
Artistic License Cars: Sheldon claims Penny's car's check engine light is on, and promptly freaks out. Penny's car is a 1985 Volkswagen Cabriolet, made before check engine lights were available in Volkswagens (1991-93 Cabriolets sold in California were required to have OBD installed. All other 1979-93 models were not equipped). Sheldon goes on to claim it weighs 4,400 pounds (1995.80 kilos). It doesn't. The GVRW of a Volkswagen Cabriolet is 2,200 pounds (997.90 kilos) (or 2,400 pounds/1088.62 kilos , depending on options and year).
Nearly every vehicle appears to have had its head restraints, rear-view mirror and sun visors removed, presumably to provide a better view of the actors.
The theme song has the line "Neanderthals developed tools." Homo habilis developed tools long before Neanderthals evolved.
Artistic License Law: In-Universe by Sheldon when he represents himselfnote There's a saying when it comes to representing oneself in court: He who represents himself in court has a fool for a client. On top of this, Sheldon was photographed doing it, so he doesn't have a defense. and tries to fight a ticket for running a red light while driving Penny's car. His defense is little more than blaming Penny for goading him into running the light and owning the carnote Because he was driving, he is 100% at fault as he could have ignored her advice; Penny, as a passenger, cannot be held responsible for his actions — the fact it's her car is irrelevant; she wasn't driving, claiming it was necessary and therefore legal for him to run a red light because Penny's shoulder was dislocated,note It's not, and a dislocated shoulder isn't life threatening. A life threatening injury may have tipped the balance, but it's not likely, because the police and/or judge would probably say an ambulance should have been called and that it's unconstitutional for a camera to issue a ticketnote it's not; red light cameras are entirely constitutional. The judge rules him guilty, which Sheldon tries to contest through incredibly disrespectful backtalking and ends up in jail for contempt of court.
For that matter, that's not how camera-issued tickets work. Sheldon mentions he received three demerits; in the state of California, tickets issued by red light cameras carry a fine and a maximum of one point, and even then, not all violations are issued with a point. Then again, it could be a sign that he screwed that badly that the judge went through the trouble of increasing the sentence (generally possible, though difficult).
Artistic License - Space Exploration: Theres simply no chance that Howard Wolowitz would even have been considered for the astronaut program. Going into space is (still) an extremely hazardous undertaking that requires a singular type of person with the physical, mental and emotional resilience and fortitude to handle whatever is thrown at them. Howard with his physical frailties (including asthma, transient idiopathic arrhythmia, prone to seasickness, a very high genetic disposition towards heart disease etc.) and emotional instability wouldnt have gotten a foot through the door. In Real LifeNASA would have brought him in as a consultant to train a real astronaut how to install the telescope he designed and constructed.
Stuart has been hanging around the group since Season 2, showing up a couple of times a year but never really significant. Season 6 practically upgrades him to main cast, at the least supported by Word of God that he will have an expanded role. While he didn't stay in the main cast listings for long, unlike Leslie Winkle he still shows up more often than before and usually with a significant role involved.
Leslie Winkle start from this to Demoted to Extra. She showed up three times in the first season, and her character was liked enough that the production team announced her as becoming a regular early in the second season. After about four episodes in, they quickly realized that she worked largely because she was a staunch, stubborn Arch-Enemy to Sheldon with no real room for her own stories or even Character Development. They quietly put her character aside and she shows up more sporadically since.
Asexuality: This is Sheldon's "deal." He's familiar with the concepts of physical or romantic attraction, but doesn't apparently experience those things himself. Any time he "clicks" with someone in a romantic way, it is always juxtaposed with a common scientific enthusiasm. While the possibility of sexual attraction has appeared from time to time (when Amy kisses him in Season 4, he says "Fascinating", which could indicate that he found the experience pleasurable or at least interesting), he is written largely as someone who puts intellect and science first and mocks his friends for not doing the same.
Leonard: I can't believe you're going to have Howard choose between sex and Halo! Sheldon: No, I'm asking him to choose between sex and Halo 3. As far as I know sex hadn't been upgraded to include hi-def graphics and advanced weapon systems. Leonard: Right, all sex has is nudity, orgasms, and human contact. Sheldon:My point.
In the Season 3 episode The Adhesive Duck Deficiency, Penny falls in the shower and dislocates her shoulder. Sheldon spends more time whining about the possibility of getting injured driving than appreciating the fact that he got to enjoy Kaley Cuoco "in the altogether."
Similarly, his Not-Girlfriend / Distaff Counterpart Amy Fowler refuses to touch or have sex with him. But as she hangs out with Penny, she displays more signs of sexual repression rather than straight asexuality, along with hints towards seeing the appeal of either side. Further realized when Amy gets roaring drunk and demands to know what or how much it would take for Sheldon to "take her to that skeezy motel and have his way with her" and later, when asked if Sheldon's knocking annoys here, says that she "plans to put his love of repetition to good use."
Joked about in Season 9, when Sheldon is contemplating what to give Amy for her birthday, he consults Penny and Bernadette for help, since they might know better what Amy might want. The first two suggestions don't really seem very interesting in Penny's view, and she asks what the third option is, to which Sheldon answers: "I was thinking of having coitus with her." Cue Penny snapping the wineglass in her hand in half.
Ask a Stupid Question...: When Penny locks herself out of her apartment and has to call a locksmith, Sheldon asks her if she would like to wait in the guys' apartment.
Penny: No, Sheldon. I would rather sit on this freezing floor, sobbing like a three year old.
Sheldon: Oh, okay. (Goes inside. Penny sighs in exasperation and runs in.)
In "The Large Hadron Collision," Penny is throwing up in the bathroom when Leonard asks what's going on.
Penny: I'm having a tea party, what do you think's going on!?
Also invoked by Penny, who knows that Sheldon always knocks on her door in a certain way with three knocks and then saying her name:
Sheldon: (Knock, knock, knock)
Penny: WHO DO WE LOVE?
Sometimes Penny has clever responses for Sheldon:
"What's the gist, physicist?
As You Know: Lampshaded by Sheldon when Leonard is filling him in on developments in the A plot as a lead in to part of the B plot (specifically that of Howard and Bernadette getting back together):
Sheldon: Why on Earth are you telling me all this? Leonard: I don't know... sometimes your movements are so lifelike I forget you're not a real boy.
Attention Deficit... Ooh, Shiny!: Sheldon. Penny sometimes, most often when she attends any of their science lectures but there is also this gem "My mother smoked pot when she was pregnant with me and I turned out fine... Oh, more wine!"
Authentication by Newspaper: When Leonard is getting ready to go to the Bakersfield Comic Con, he takes a picture of him kissing Penny's cheek while she holds the day's paper to prove to the other attendees that he not only has a girlfriend but that she is also hot.
Author Vocabulary Calendar: Sheldon and Amy might have a game in which they decide on their word of the day. In "The Desperation Emanation", they choose 'cornucopia' and 'mellifluous' for the next day.
Awkward First Sleepover: Amy is excited to have her first slumber party at Penny's with Penny and Bernadette. She's in her thirties and Penny and Bernadette pity her as she had no friends prior to meeting her boyfriend Sheldon and his social group. She's very awkward about the whole sleepover, e.g. she thinks girl talk is talking about female anatomy, she wants to play all the games (like truth or dare) and even tries to make a pass at Penny off-screen, claiming her internet sources list lesbian experience as a vital part of sleepovers.
Ax-Crazy: The (fictional) B-MovieSerial Ape-ist features a "psychotic" gorilla who kills women with an axe. In one known scene, the gorilla kills a character played by Penny. In the sequel, Penny turns into the killer gorilla herself and has homicidal urges.
Back from the Dead: Penny's character died in the (fictional) B-MovieSerial Ape-ist. In the sequel Serial Ape-ist 2: Monkey See, Monkey Kill, a Mad Scientist clones her. Since the clone retains the memory and personality of the original, this is treated as a resurrection.
Bad "Bad Acting": Sheldon and Amy trying to put on a web series "Fun with Flags." They always stare straight into the camera, even when having a "conversation" with each other.
Sheldon is not a very good liar. In "The Lizard-Spock Expansion," Leonard is going to sneak out and see Stephanie, but he tells Sheldon to tell Raj and Howard that he is going to the office. Sheldon's delivery of this line is very unconvincing due to his unnecessary emphasis on the word "office" and his exaggerated innocent expression. Though it turns out that Sheldon is only bad at coming up with a lie on the spot. If given ample time, not only can he come up with a plausible and convincing lie, he can even come up with falsified evidence to support it.
Bare Your Midriff: Penny for the first 2-3 seasons, along with a bikini in one season 8 episode.
Barrier-Busting Blow: Penny is casually climbing upstairs, minding her own business, when Sheldon and Leonard's door bursts apart and a killer robot of their own invention rampages into the hallway, making her flee in terror.
Basement-Dweller: Howard, only without the basement apartment. He essentially lives like he's still 15 for American standards. The norm of an adult Jew still living with their mother is even commented upon several times.
Though this seems to be more his mother hanging on to him than him wanting to stay though in his mind he likely does want to stay.
Amy asked Sheldon to pretend to be her boyfriend so that her mom would get off her back. Sheldon initially confused it for an invitation to actually be her boyfriend, and was relieved when that wasn't the case. As they meet her mom over web cam, he made certain to talk about how much sex they have together.
Raj is set up by his parents with an Indian girl who admits she is a lesbian and wants to marry him to dispel suspicion. A twist is that she (and others, including his friends and parents) think that Raj is in the closet as well so it would be a mutual beard relationship.
This was the excuse used by Sheldon when he discovered that Kripke was further along in his research than Sheldon was. When Kripke calls him out on this, he gives Sheldon an out by stating that Sheldon must be Distracted by the Sexy. Sheldon, not willing to admit his mental inferiority to Kripke , readily agrees. He then goes into extremely inaccurate detail about his sex life. Includes the gem "I gave her genitals a good rogering."
In this same scene, when Kripke asks if they use "toys" meaning the adult sense of the word, Sheldon naturally assumes he is talking about his collection, not making the connection.
Kripke: What about toys? Sheldon: Well, yes, there's lightsabers and action figures... Kripke: You're a FWEAK, Cooper!
Beast Man: Penny plays a Beast Woman in the (fictional) B-MovieSerial Ape-ist 2: Monkey See, Monkey Kill. The character has mostly human features, but gorilla hands and feet. She struggles with violent, animalistic urges, triggered when she seen bananas. In one scene of the film, she bites off the finger of her doctor's receptionist. She's slowly turning more and more into a gorilla, with the last part being her cleavage.
Berserk Button: Howard Wolowitz doesn't like being reminded that he doesn't have a PhD. Every time he tries to start something, Leonard tells him to sit down and he complies. He might not have a PhD but he recognizes he's too puny to do anything about it.
Sheldon has numerous examples:
Perhaps it would be best to begin with an in-universe listing...
Raj: What did you do? Did you change the contrast or brightness settings on the television?
Raj: Did you take a Band-Aid off in front of him?
Howard: Did you buy generic ketchup, forget to rinse the sink, talk to him through the bathroom door?
Raj: Adjust the thermostat, cook with cilantro, pronounce the T in often?
Don't mention Wil Wheaton around Sheldon, unless you want a "WHEEEEEAAAATOOOOOONNN!" that would make Shatner proud. They made up at the end of "The Russian Rocket Reaction" and are now good friends (according to Sheldon, anyways). Unfortunately, Brent Spiner then inadvertently replaces Wil Wheaton on Sheldon's Mortal Enemy list.
And don't sit in Sheldon's spot on the couch. You will regret it.
While Sheldon is perfectly fine with cheap shots aimed at his mother, do not insult his Meemaw.
Being let down by his friends, but especially Leonard, is another one. After Kripke humiliated him on NPR, his misery is compounded when he finds out Leonard laughed.
Sheldon usually doesn't resort to physical violence, but question the legitimacy of his work and back up your claims with tangible proofs and all bets are off.
A minor example, but only his mother and sister are allowed to call him "Shelly". Furthermore, only his Meemaw is allowed to call him "Moon Pie".
Amy is a new one — Sheldon actually physically assaulted Leonard (via a karate chop to the neck), when he mistakenly believed that Leonard had been up to something with her. He also attacked Bert the geologist when he said he's over Amy now that he became rich with a grant, but looking at him, Sheldon literally hurt himself more than he hurt him.
Oh and speaking of Bert, it's killing Sheldon someone in that particular science, geology, is given a grant.
Raj: I'm telling you dude, the only way to make you feel better about Penny going out with other guys, is for you to get back on the whores. Howard: ... "horse". Raj: What? Howard: The phrase is "get back on the horse"... not "whores". Raj: That's disgusting, dude!
Beta Couple: Both Bernadette/Howard and Amy/Sheldon are relatively stable compared to Penny and Leonard's relationship. As of "The Herb Garden Germination", Howard and Bernadette are engaged — and in the Season 5 finale, they tied the knot.
Between My Legs: This shot is used with Penny's legs framing a remote control car with a camera that's trying to see... well, between her legs.
Beware the Nice Ones: Bernadette, several times in Season 5. In "The Skank Reflex Analysis", when she snaps on Raj, after Leonard reveals to the group Raj's crush on her. Bernadette flips out and angrily confronts Raj, berating him to tell Howard that nothing is going on between the two of them. This is somewhat Lampshaded in the scene.
Bernadette, when pushed far enough (which doesn't take much due to her short temper), screams/talks in the same manner as Howards's mother; he finds this sexy. Although Bernadette is more of a Yangire than an actual nice one.
Penny assumes her friend Emily is automatically nice because she's deaf, and people with disabilities can't afford not to be kind to everyone. Not quite.
Big Brother Instinct: Sheldon briefly becomes very protective of who his twin sister dates, though subverted as its only because he comes to the conclusion that residing in her loins possibly lies the potential building blocks for her to have an offspring who is another remarkable individual like himself; Sheldon 2.0, if you will.
Like the supporting character in a movie where they disappear for much of the second reel, only to return in the third act coming to the rescue, I have a solution... (complete silence) Odd, they usually cheer.
Sheldon lets one out when he realizes that he locked himself out of his apartment, ruining his perfect night alone.
Sheldon when a "terrifying" song bird flies through the apartment window and lands on his couch space.
Raj when he gets too attached to the female voice on his phone, has a sex-dream about her as a woman, only to find out that once again, he can no longer speak.
Leonard gives a spontaneous Big "NO!" the moment after Bernadette introduces her ex-boyfriend Glen, to Penny, in "The Love Car Displacement", as a ride for Penny back to Los Angeles. Leonard is understandably worried as it is strongly implied that Glen is well-endowed, and Leonard was attempting to rekindle his romance with Penny.
Bigger Is Better in Bed: Bernadette's old boyfriend Glen in "The Love Car Displacement" is strongly implied to possess a massive cock due to his physical size. The episode revolves around the guys' notion that Bigger Is Better in Bed and their insecurities about that.
It's strongly implied the guys were assuming Glen was well-endowed due to his race as well (he was played by Rick Fox)
Bilingual Bonus: Amy Farrah-Fowler invokes this in Episode 22 of Season 4. You can still get the gist of the sentence, but Amy was called a whore in Spanish.
Amy Farrah-Fowler: I used to take my lunch down to the maintenance room and eat with the janitor. It was nice until his wife called me a 'puta' and made me stop.
Chinese speakers will recognize that Sheldon asking the Chinese restaurant owner to "show me your mucus" in "The Tangerine Factor" is indeed a very mangled attempt to say "show me your tangerine peels".
On the whiteboard in shot during The Staircase Implementation are references to B-Stoff and C-Stoff. Anyone fluent in German who also knows a little about Werner von Braun, who designed the V1 and V2 rockets used to blitz England in 1944-45 and went on to lead the American space race, will recognize the x-Stoff references as shorthand for the various lethal components of wartime German rocket fuels. And of course, in this episode, Leonard gets hold of some NASA rocket fuel and ends up destroying the elevator with it. As surely as if he'd dropped a V-2 down the shaft.
The guys occasionally converse in fluent Klingon. In one episode, Sheldon and Leonard do so to prevent Penny and Amy from understanding them; the girls respond by talking in Ubbi Dubbi, confounding the guys.
Birthday Episode: "The Peanut Reaction". After learning that Leonard has never had a birthday party, Penny decides to throw him one and drags the others into helping her. It doesn't go well, naturally. The title, for instance, refers to Howard triggering his peanut allergy as a desperate attempt to keep Leonard away until the party.
The Season 9 episode "The Celebration Experimentation" has Sheldon get a proper birthday celebration with friends after getting mistreated on past birthdays, just as noted in the next trope below. But at first, Sheldon is so briskly overwhelmed by it he has a panic attack.
Birthday Hater: Sheldon has some mental scars from past birthdays relating to his general aversion to socialization. Leonard is pretty apathetic as far as birthdays go because his mother didn't like the concept, but appreciates the gesture when his friends plan a surprise party for him.
Sheldon finally has a positive & comforting birthday celebration in "The Celebration Experimentation." But before he can celebrate he has a panic attack due to being adapted to much abuse on his past birthdays that such a positive change in this birthday's overwhelming.
Bitch in Sheep's Clothing: Priya, since she refused to let Penny see Leonard when they were dating, pressured him to wear contacts despite the fact that they put him in the hospital, strung him when she knew that she was going back to India, and slept with her ex-boyfriend when she was back in India. Not to mention telling Leonard she'd break up with him if he didn't sign the ridiculous new roommate agreement, because Sheldon was threatening to tell her parents about their relationship.
Raj can also be a bit like this. Howard lampshades it in "The Zazzy Substitution".
"I have no difficulty believing you're not butter."
Leonard, Penny, and Sheldon watch an episode of Oshikuru Demon Samurai. The actual dialogue heard played is from real series Boogiepop Phantom. Oshikuru is a fictional anime series also mentioned in Two and a Half Men.
However, in "The Zarnecki Incursion," many of the WoW references were true to the game.
If you pay attention during the cafeteria scenes at the university, the coke cans say things like "Dr Peeper".
Blatant Lies: When attempting to get information out of a male character in World of Warcraft, Raj (playing a female character) sighs and volunteers, "I see where this is going. Fine. I'll have sex with him." Everyone gives him a look and Leonard responds "That's not where this was going." Raj gives the most unconvincing shifty-eyed look ever while saying "Oh. Good. Because I would hate that."
Bernadette sets Leonard up on one in Season 4. Leonard finds his date to be completely miserable.
Blipvert: The title sequence presents a chronological series of together 109 images of the great moments and inventions in human history. Even in the early days, each image appears for a fraction of a second, but the pace really picks up when we get to the Industrial Revolution; progress occurs so quickly that each image appears for only a single frame.
Blue-and-Orange Morality: Sheldon Cooper has a unique and well-developed sense of right and wrong that makes absolute perfect sense... to Sheldon. To everybody else, this can often make him come across as hard to understand, awkward, arrogant, selfish, and insensitive at times. Justified by whatever unnamed and undiagnosed personality disorder he exhibits, which makes him see the world in pretty black-and-white terms, have obsessive-compulsive tendencies, and have a general inability to understand social mores.
His weird personal moral rigidness often comes bouncing back in surprising ways. For example, he loans Penny a large amount of money and is completely casual about when she should repay him, reasoning that it is money he isn't using and will not need.
Blunt "Yes": A common gag involves one character making a convoluted yes/no question, often rhetorically, only for another character to answer it bluntly.
Body Backup Drive: Sheldon wants to do this, but is concerned that the technology won't be ready by the time his body dies.
Bollywood Nerd: Raj milks this for all its worth, claiming to have grown up in poverty before moving to America to pursue his dream of becoming an astrophysicist.
Howard: Your dad's a gynecologist! He drives a Bentley!
He later admitted that he grew up in a large home with servants and according to him "We don't allow our poor people to have dreams."
Book Dumb: Although Penny is more street-smart, sociable, and tolerant than any of the guys, she's easily exasperated and put off by even trying to learn anything related to science. Except that fig Newtons are named after the town in Massachusetts, not the scientist.
"Don't write that down!"
This dynamic is reversed in "The Thespian Catalyst", where Penny, during an acting lesson to Sheldon, suggests they read lines from Tennessee Williams' Pulitzer Prize-winning play, Cat on a Hot Tin Roof. Sheldon has no idea who Tennessee Williams is, and insists they work with his own Star Trek fanfiction.
During one episode, Bernadette and Amy are talking about some complicated scientific subject, and Penny chimes in with comments that are right up to snuff with them. As they look on astonished, she quips, "See, my phone is as smart as you two!" with a big grin on her face.
Book-Ends: The final shot of the entire show is the gang enjoying takeaway while a slow version of the theme song plays, referencing the intro.
Book Smart: All the main characters except Penny are brilliant when it comes to science and academics.
Brains and Bondage: Dr. Elizabeth Plimpton from "The Plimpton Stimulation." Smart enough to earn Sheldon's regard; tries to get Raj, Howard, and Leonard into a four-way and is very enthusiastic about sexual roleplay.
Sheldon: Let me save you some time, my answers to the standard Rorschach ink blot test are A) a bat, B) a bat, C) a bat and D) my father killing my mother with a hypodermic needle.
Also, Sheldon's response when Raj is facing deportation:
Sheldon: I believe it means that the U.S. Government is going to expel him from the country. He could then either return to his native India, emigrate to another country thats willing to accept him, or wander the high seas as a stateless pirate. Personally, Id choose pirate.
Break the Haughty: Sheldon is sometimes caught up by karma. The rest of the gang occasionally succeeds in proving him wrong, humiliating him or shutting him up but it's subverted by the fact that he never seems to lose his arrogance. Usually, he won't admit he was wrong, even to himself, and will go through incredible contortions to maintain his self-image as perfect.
Breakout Character: Both Bernadette and Amy Farrah Fowler started out as sporadic recurring characters introduced in the third season and given their own little plot lines in the fourth. While they may not always show up unlike the core 5, they are credited as stars in the episodes they appear, and have appeared much more frequently than before. Starting from Season 5, they can be expected to appear in any given episode and get just as much focus as any of the other characters. By the end of the show they were an integral part of the main cast with equal screentime.
In Season 1 Episode "The Grasshopper Experiment," the guys discuss their enjoyment of Fiddler on the Roof. At the very end, Sheldon plays and sings a drunken song from the play.
In one episode, Wolowitz, Raj, and Leonard reveal in a passing joke that they always thought that Sheldon reproduced asexually via mitosis. At the very end of the episode, Leonard has a nightmare about this very thing happening, after not being mentioned for half an episode.
There's an extremely delayed one hiding in the first episode. The "200-pound transvestite with a skin condition" shows up in the flashback episode at the end of Season 3.
In one scene, Penny is violently breaking up with unseen boyfriend. She storms to the guys' apartment, opens the window and throws out his iPod. When Raj walks in moments later, guess what he found on the street? Jackpot, an iPod.
In "The Friendship Algorithm," Sheldon mentions his fear of birds. It's revisited in Season 5.
In "The Creepy Candy Coating Corollary", Leonard says "Warlord beats Troll, Troll beats Elf, Elf beats Water Sprite, and basically everything beats Enchanted Bunny". During Sheldon and Raj's final match with Wil Wheaton and Stuart, Sheldon feels bad for Wil's grandma dying, so he plays Enchanted Bunny... and loses.
In Season 3 episode, in the first scene, Raj, Howard and Leonard run down the stairs shouting "Kites ho!", incurring Sheldon to give a speech on the correct use of the term 'ho'. Later, when Sheldon asks why Leonard went through the trouble of learning the rules of American football so as not to embarrass himself in front of Penny's friends — and therefore still be able to see her — when he could have more easily paid someone else to have sex with him.
Sheldon: Am I correct in assuming that your attempt to be accepted by Penny's peers is based on your desire to continue your mating privileges with her? Seems like an awful lot of trouble to go through for intercourse. Don't you have access to women who will do it for money? By the way, another accepted use of the term 'ho'.
In The "Hamburger Postulate", Sheldon points out that the name "The Soup Plantation" is odd since you can't grow soup. A few minutes later, after an unrelated conversation, Leonard remarks that you can grow the ingredients for soup.
In Penny's car, a 'check engine' light is on and people keep reminding her that she should do something about it. Finally pays off in Season 7 when Penny's car breaks down for good.
Combined with a running gag: Everytime Sheldon is called either 'insane' or 'crazy' he counters by saying that his mother had him tested. Until S 05 E 06, when Leonard calls him crazy in his mother's presence, she mentions that she *did* have him tested, and the doctor said he was fine... but that she should rather have consulted a specialist.
In "The Prestidigitation Approximation", Leonard suggests the possibility of Priya wearing Raj's Uhura costume during sex. Six episodes later, Raj hears their "astronomically inaccurate Star Trek sex" from the living room.
In Season 6, one episode opens on Sheldon discussing the possibility of a Frisbee sized wormhole. At the end of the episode, Raj and Howard discover he's created one. Turns out it's a prank.
An almost-literal brick joke happens in Season 2, when Howard tests his modifications to the space toiletnote "It's classified!" with his mother's meatloaf. The toilet shoots the meatload upward, and it sticks to the ceiling. It falls back down, just like a falling brick, by the end of the episode.
In Season 6, the crew of the International Space Station make Howard clean out the space-toilet he designed, as revenge for the incident back in Series 2, when it malfunctioned and covered the entire interior of the station in excrement.
In "The Convention Conundrum", Sheldon is scared to call Carrie Fisher because he thinks she might be a little crazy. Later, when hanging out with James Earl Jones, James Earl Jones confirmed she is a bit crazy from James Earl Jones ringing her doorbell and then running.
Howard's exclamations of "I'm Batman!" while in full costume, which are hilarious both due to his pint-sized stature and overall imitation of Christian Bale's deep and gravelly voice in The Dark Knight Trilogy.
Brainy Brunette: All of the main four have brown hair, and all have anywhere from above average to freakishly high intelligence levels. Leslie Winkle and Sheldon's graduate assistant, Alex, are female examples.
Leonard, at least according to his mother and Sheldon. Both express the opinion that Leonard is slumming it by doing no original research and baffled at why he's content confirming the results of experiments done by others. Leonard does point out that confirming results validates the major scientific experiments and that just because it's not cutting-edge research, doesn't mean its not very important work. When Sheldon came up with a new theory that was highly praised, Leonard was quick to remind him that he created the experiment that proved it; the scientific community wouldn't just "take his word for it".
Sheldon seems to be a fairly accomplished cook. Amy notes that his sourdough bread is excellent and he prepares Leonard a delicious looking and pretty complex breakfast in bed (Frodo-shaped pancakes, butterscotch scones etc). Despite this, he almost never cooks (instead ordering different takeaway food every night), and Leonard usually does any home cooking, despite Penny noting that "he can't."
Broken Aesop: The Habitation Configuration. This episode has Amy being hard and ruthless about Wil Wheaton's "wooden" acting on Fun with Flags, and he rightfully calls her out on being a pain in the ass. Amy then asks him to leave, which Sheldon objects to, and then she acts like a Clingy Jealous Girl about it. Throughout the episode, Sheldon is told by the likes of Leonard and Penny that he should have had Amy's back. At the end of the episode, when she is treating LeVar Burton in the same manner, Sheldon comments, "I don't know what she's talking about, but I'm obligated to agree with her. She's my girlfriend." Sheldon's behaviour is supposed to be typical of his oddness, but in fact, other than the two said celebrities, he is the Only Sane Man throughout this situation.
Amy: *drunk* What would it take for you to go into that liquor store, buy a bottle of hooch, then go to the motel over the street and have your way with me?
Amy: Proposal: one wild night of torrid lovemaking that soothes my soul and inflames my loins.
But Now I Must Go: Amy's time traveler Fan Fic character Cooper uses this reasoning. He stays in the 19th century for a while, and then explains to his love interest Amelia: I cant stay, but I will never forget you. Just before attempting to leave with his Time Machine.
Amy: Are you familiar with meme theory? Sheldon: I'm familiar with everything... but go on.
Whenever someone is feeling bad, Sheldon will make them a hot beverage, the beverage flavor depending on the seriousness.
Sheldon: "I'll make you some tea."
Leonard: "I don't really want any."
Sheldon: "It's not optional."
Butt-Monkey: All four of the main male characters, in different ways:
Leonard. The show has gone out of its way, particularly in recent seasons, to make his life more miserable...and it's always Played for Laughs, regardless of Leonard's progressively damaged psyche.
Sheldon is often on the receiving end of a lot of humiliation and punishment, not that he doesn't bring it on himself, though.
Howard is often made fun of by everyone else (sometimes, even Penny) for his lack of a doctoral degree, his relationship with his mother and his being a Casanova Wannabe. He was also the Butt-Monkey to the other astronauts when he was in the space.
Raj's inability to speak around women often makes him this, as he has to whisper his comments to Howard, who pretends he said something completely different.
Stuart Bloom as well for that matter. Everything he says is depressing. His idea of being "cocky" is to claim that he's "unobjectionable." He can be stood up by a stray cat.
Alex. Only natural since she is Sheldon's assistant.
California University: Averted; Caltech is of course a real (and well-known) university in Pasadena, CA. In a strange variation though, given the ages of each character it is unlikely they would have stayed with the same university as long as they have, at least since about 2002. It's largely just practical for the purposes of a show but it could also be that they are just comfortable with the current status of their careers.
Also averted in the sense that everyone in the cast grew up in different locations and went to school at different places, they all found a job at Caltech. Raj is from India and went to Cambridge, Howard appears to be a local but he went to school at MIT, Leonard is from New Jersey and went to Princeton, and Sheldon is from Texas and went to East Texas.
Early in the second season, you catch the tail end of a conversation Penny was having with a boyfriend of the week, where she was trying to explain Schrödinger's Cat to him. In the first season, Sheldon used that principle of quantum physics as an analogy towards the possibility of a relationship between her and Leonard. This also doubles as foreshadowing, showing that Penny is starting to enjoy or at least retain the scientific concepts and mental exercises the others often explain to her.
In the fourth season, Penny gave Leonard a surprise kiss in front of her father, trying to placate him by pretending her and Leonard were together. Leonard stumbled back into his apartment and explained what happened to the guys, and they started joking over Leonard pining after Penny again, with Raj making a direct quote from the pilot episode as a Leonard classic "Our children will be smart and beautiful."
In Season 1, a sick Sheldon asks Penny, who is nursing him, to sing him a song his mother use to sing to him when he was sick, "Soft Kitty." The next season, Sheldon was homesick after being locked out of his apartment and asks Penny to sing the song to him, seeing homesick as a type of sick. The following season, after Sheldon is betrayed by the guys, Penny attempts to console him with "Soft Kitty," but is interrupted by Sheldon since 'Sad is not sick.' Again in the third season, when Sheldon is taking care of Penny after she dislocated her shoulder and was doped up on pain medication, she asks him to sing the song to her. In Season 5, Sheldon's mom actually sings it to him.
Way back when Penny and Leonard started dating, Leonard makes a reference to The Black Eyed Peas, only for Penny to point out he had no idea who they were until he started dating her. Fast forward a few seasons and we catch Leonard rocking out to "I've Got a Feeling" on his way to work.
In the first two episodes of the series, Sheldon and Leonard talk about "Louis/Louise," the transvestite cop who was the previous occupant of Penny's apartment. Later, during the Whole Episode Flashback "The Staircase Implementation" in Season Six, Leonard knocks on the door of that apartment, which is opened by Louis—who's wearing a full evening gown and diamond earrings.
Way back in season 1, Dennis Kim tells Sheldon string theory is a dead end and he'll see it one day. Well...
In season six, Amy says that she has a five-year plan to get Sheldon to marry her. Sheldon proposed in season ten. They married in the end of season eleven; thus she timed it perfectly.
Sheldon recalls Leonard's insistence on his babies with Penny being "smart and beautiful" during Sheldon's Nobel Prize acceptance speech, and actually agrees with the statement now that they're expecting instead of scoffing at the idea.
Calling Your Bathroom Breaks: Sheldon actually insists on a bathroom schedule, occasionally attempting to discuss it with others. Leonard's mother, likewise, stands and says "I have to urinate," before going to the bathroom.
Came Back Wrong: Penny's character died in the (fictional) B-MovieSerial Ape-ist. In the sequel Serial Ape-ist 2: Monkey See, Monkey Kill, a Mad Scientist clones her. Since the clone retains the memory and personality of the original, this is treated as a resurrection. Only a mistake caused her DNA to be mixed with that of the Killer Gorilla who killed her. So the clone is more Beast Man than human and has killer urges inherited from the gorilla.
In the episode where Raj gets in People Magazine's "Top 30 under 30", he brags about it to some guy sitting nearby. This turns out to be Charlie from Two and a Half Men, who tells him to call when he's on the cover. (This is a direct reference to the fact that Charlie Sheen has indeed been on the cover of People many, many times.)
In Season 3, Lewis Black plays an entomologist who settles a dispute between Sheldon and Howard.
Cannot Spit It Out: In the last few episodes of season two it becomes apparent that Penny has started to fall in love with Leonard, but was not ready to tell him (likely because of how awkward things got when they tried dating earlier). In the season finale "The Monopolar Expedition", Leonard and the others are preparing to leave for a three-month long expedition to the North Pole and Penny starts acting oddly: upset about not being informed earlier, buying him a blanket (with sleeves) and giving him an unusually long hug goodbye. Leonard catches on to the hints and tries confronting her about it, which she deflects and denies. Once Leonard leaves she privately admits sadly she wished he wasn't going. When they return the first thing she does is plant a big kiss on him, seeming after having plenty of time regretting not telling him how she felt.
This is once again brought up during "The Justice League Recombination where, it's clearly evident that Penny is regretting her break up with Leonard and is only dating Zack simply to distract herself. When Leonard questions her to why she's sad, she's unable to tell him and instead chooses to attend the comic book store party instead.
Penny is also reluctant to tell Leonard she loves him due to her Commitment Issues, she evetually does tell him after they get back together and the emotional gravity of the moment makes her cry.
Played for Laughs In "The Cooper Extraction", where the gang explore What If? scenarios with the premise that Sheldon isn't in their lives. Leonard and Sheldon aren't roommates, and Leonard and Penny are not neighbours. In Penny scenario, Leonard meets Penny at the Cheesecake Factory and wants to ask her out. He fails to say anything other than asking for directions to the restroom. Preventing any relationship from occuring.
Cannot Tell a Joke: In "The Hesitation Ramification", Sheldon attempts to develop a unified theory of comedy to make anyone laugh at any time. Pretty much every attempt he makes to tell a joke falls into this category.
Sheldon. It helps him get over his stage fright, but boy, does it send him off the deep end. In a later episode, he uses tequila as an impromptu mouthwash and admitted he might have swallowed a teeny bit. He immediately follows by an offhand "I love you so much" to Leonard. Even coffee to keep him awake makes him quite hyperactive.
Likewise, Amy. It not only renders her incapable of multiplying 14x16 and causes massive vomiting followed by passing out, but she also flirts with and kisses Sheldon.
In an interesting case of Reality Ensues, Raj finds that he can't talk to woman without a little bit of a buzz (it has sometimes just required one sip or at least the Placebo Effect). Initially, while capable of talking to women he also very quickly became drunk and obnoxious. As he continued, his ability to hold his liquor improves drastically, and that trailed into his success with women.
Captain Obvious: Sheldon. An example in "The Financial Permeability", when Penny tells him that she's behind on her bills:
Sheldon: It occurs to me you could solve all your problems by obtaining more money.
When Leonard's car gets stolen in "The Bakersfield Expedition":
Sheldon: STEALING IS AGAINST THE LAW!
Caretaker Reversal: In Season 1, Sheldon gets sick and makes Penny take care of him. In Season 3, Penny gets injured and makes Sheldon take her to the hospital and take care of her afterwards. What connects these two instances most solidly is the song "Soft Kitty." Sheldon teaches the song to Penny to sing to him ('cause that's what his mother did when he was sick as a youngster). Then, when Penny is injured, she makes him sing it to her.
Penny: Sing "Soft Kitty" to me.
Sheldon: "Soft Kitty" is for when you're sick. You're not sick.
The actors who play Leonard and Leslie previously played David and Darlene on Roseanne. Sheldon's mother is played by Laurie Metcalf, also from Roseanne. Christine Baranski co-starred in Cybill, also written/produced by Chuck Lorre (who was writer/producer for Roseanne). Bernadette's father is played by Casey Sander, who co-star Ed in Lorre's Grace Under Fire
Judd Hirsch as Leonard's father. Johnny Galecki mentioned in interviews that he was inspired by Hirsch's role in Taxi when it comes to being the Straight Man of the cast, and was influential in bringing him on the show.
Catchphrase: Sheldon created his own with "Bazinga!" whenever he attempts a joke or prank. Unusually, it is only used a handful of times a season.
A species of bee has been named "Euglossa bazinga".
Also, "Excuse Me" when Sheldon has to interject with someone's statement.
"Rats!" and "Drat!" when Sheldon is unsuccessful at something.
"Here we go...." whenever someone causes Sheldon to go into an explanation he has apparently said previously numerous times. Usually said by Leonard.
"I'm not crazy. My mother had me tested." Used by Sheldon.
The episode "The Gothowitz Deviation" features a one-shot character with her own catch phrase. Sarah the Goth girl finishes most of her lines with the phrase: "Not that anyone cares."
"You're in my spot." Used by Sheldon when someone sits in his spot. Alternatively rendered as "that's my spot" or "that's where I sit".
"Good lord!" when Sheldon when he is shocked, though ironically Sheldon is atheist.
Penny's favorite slur is "Rat bastard".
Catfight: Occurs when Penny and new neighbor Alicia's rivalry over her leading Raj, Leonard, and Howard on culminates in a "What're you gonna do about it, bitch?"
Somewhat lampshaded by Wolowitz:
Howard: Oh, my God... GIRLFIGHT! [pins Leonard's arms behind his back] Leonard: What're you doing? Howard: I know you, you're stupid enough to break it up!
Almost reached that point with an argument between Amy and Bernadette that spilled over from an argument between Sheldon and Howard. The only thing that prevented it was the first swing hitting Penny in the face.
Cathartic Chores: In the last season, Amy is distressed because she feels too much pressure once she's told she has a chance to be the fourth woman to receive Nobel Prize for Physics. As such she could inspire numerous women to choose a career in STEM. (Two scientists stole a credit for her and her husband's groundbreaking work and her public outburst at them didn't help at all.) They try sensory deprivation therapy: Sheldon is calmed down, but Amy is still anxious and once they get home, she starts scrubbing their fridge.
"Cavemen vs. Astronauts" Debate: Often done with the guys getting into massive arguments over geek items or general discussions like whether mummies and zombies are basically the same thing. Although it gets epic when the girls try experimenting with reading The Mighty Thor and found it to be stupid, but ended up getting into a complicated and intense debate over the mechanics of lifting Mjölnir.
Penny: If Harry Potter's wand can make decisions why not Thor's hammer? Amy: If you are going to start comparing wands and hammers... I cannot take you seriously!
The geeks have a discussion about both Danica McKellar and Mayim Bialik in one first season episode. It would've been weird enough if just the former had played a bit part later in the series, but when the latter plays Sheldon's date and eventually gets a starring role, this gets a bit weirder...
Wil Wheaton wears a t-shirt of "The Guild", which Simon Helberg (Howard) once appeared in as the "Kevinator".
Raj's dad is played by Brian George, the same actor who plays Julian Bashir's father in Star Trek: Deep Space Nine, but none of the guys (who are all avid Star Trek fans) have noticed.
Sheldon's previous flatmate was played by Steven Yeun, who plays Glenn in The Walking Dead. A few seasons later, Sheldon asks Leonard if he wants to watch that very show.
In the first season, they group mention their love of the show Scrubs. Raj later has a brief, and doomed, relationship with Lucy, who is played by Kate Micucci. Micucci was Stephanie Gooch on Scrubs.
When Nathan Fillion makes a cameo, Raj mentions loving Dr. Horrible, which Simon Helberg played a role in (Moist).
A small one, but in the season 2 episode "The Euclid Alternative", the woman Sheldon gets in an argument with over the driver's test is played by Octavia Spencer. Spencer also had a brief cameo as the check-in woman in the 2002 Spider-Man film, which Sheldon is a fan of. Her role in that film is also to have small argument over a desk.
There's been at least two references to The Simpsons. In the season 3 episode "The Einstein Approximation", Sheldon applies for a job where the woman at the counter is played by Yeardly Smith, the voice actor of Lisa.
In Season 9, Raj meets and even dumps his girlfriend to try to go out with an aspiring screenwriter played by Alessandra Torresani, who starred on Caprica. The show has also acknowledged the existence of its parent series, Battlestar Galactica (2003), with Howard masturbating about Katee Sackhoff (As Herself), who played Starbuck. Michael Trucco, who played Starbuck's husband Sam Anders, has also appeared in The Big Bang Theory as a physicist Penny dated.
With Wil Wheaton playing As Himself, Sheldon once made a direct reference to Stand by Me. Jerry O'Connell ends up playing Sheldon's brother George. Both him and Wheaton end up at Sheldon's wedding, some fans were hoping for some sort of in-joke on the matter as they cross paths.
Throughout the series, Leonard is a huge fan of the Toy Story films. Sheldon's mom is played by Laurie Metcalf, who voices Andy's mom in Toy Story.
Later in the shows run, both Melissa Rauch and Kaley Cuoco ended up playing Harley Quinn in different animated adaptations. Can't help but wonder what the guys would think watching them and hearing their voices.
Celibate Eccentric Genius: Dr. Sheldon Cooper before Amy Farrah Fowler came along. Even his dynamic with Amy isn't particularly conventionally romantic.
In the backstory, Leonard's parents only had sex in order to procreate. Once that was done, they were done.
Character Development: The show is ultimately still a sitcom and thus character development happens at a very slow pace, but the sheer length of time the show has gone on has shown an immense level of change for every character.
Leonard's crush on Penny was hampered by his low self-esteem and he wasn't a guy who understood what a relationship with a "normal" girl really meant. Through being a Dogged Nice Guy they do eventually end up together, but still having traits of being an Extreme Doormat and his desperation to stay with her did not help. When he started becoming more assertive, standing up for himself, not be so cloying and be more willing to criticize Penny's actions it proved to actually strengthen their relationship. This, in turn, had a ripple effect in his relationship with both Sheldon and his Mother.
Penny was very ditzy in the early episodes and easily confused. She was friendly with the group but kind of aloof at times, but gradually came to enjoy spending time with them and pick up on some of their science topics over the years. She later realized that being with Leonard spoiled her ability to date dumb guys. She started expanding her own education, moving on from her aspirations to be an actress and became a pharmaceutical rep. Along the way she expresses some regret towards her Alpha Bitch past and tries to treat both Sheldon and Leonard better.
When Howard started dating Bernadette, he grew out of his Casanova Wannabe tendencies and learned to be in a real relationship (it's implied that he never had a third date with the same woman before). This culminates in him being the first member of the group to get married. Howard's sincere and heartfelt apology to Bernadette after she learns how he used to be, admitting that he's no longer that creepy loner since he met her and that she's the reason why he's become a better man. This actually ends up reducing Penny to tears at how far he's come since they first met. After several seasons of Bernadette Parenting the Husband, he makes some strides to be more attentive to raising their kids and doing household chores.
Raj has come to master the art of drinking to talk to women, but not so much to become an obnoxious slob. In the Season 6 finale, he talked to Penny while completely sober. After a string of unsuccessful relationships he comes to learn that being a Momma's Boy was not an attractive trait and relying on his parents money made him spoiled and avoid his problems, so he cuts himself off from their wealth. Being self-reliant gave him a newfound bout of confidence and he started a new job at the planetarium.
Sheldon, despite all of his eccentricities and very regimented lifestyle, has come to appreciate social interaction much more. He often complained about Penny hanging around them since she didn't have much, if any, of the same interests, but has admitted he had come to enjoy her presence. In Season 5, he also began pushing against the boundaries of his regimented life more often and admitted that his life didn't fall apart as a result, and he pursued an official relationship with Amy. After years of being together with no sex involved, he grows more comfortable with acts of affection and eventually decides he is ready to be intimate with Amy.
Amy started off in the series as a straight Distaff Counterpart to Sheldon, having no sexual impulses, is condescending to others, and even speaking in a similar manner with a dry wit. She started to show an interest in social activities with Penny and Bernadette and now considers Penny to be her "bestie" (best friend). By the beginning of the fifth season, she still has a little of the Sheldon-esque weirdness about her, but is otherwise a very social and friendly individual who knows how to have fun. They end up becoming an official couple... complete with documentation, i.e. The Relationship Agreement. Amy finds her patience being tested to the extreme because of how little interest Sheldon has with physical acts, and even breaks up with him for a time to explore life without him.
Bernadette was fairly uninterested in having kids, after being burned out on children because of her mothers day care. She initially agrees to kids only if Howard becomes a House Husband, but comes around to the idea. When she does become a mother she surprises herself with how much she loves her child.
In the first episode Sheldon was basically just Leonard's even more geeky roommate with a dry sense of humor, although he still largely had the same quirks and qualities that have come to define him. The first episode has the "his spot on the couch" gag and he criticized Leonard's board of equations. But he seemed to be more socially astute (recognizing Leonard's crush on Penny and his chances with her) and not completely asexual (he appreciated the attention Penny gave him and was described as a "semi-pro" when at a sperm bank). It wasn't until the second episode that his arrogance and social ineptitude took hold (where Leonard had to make a "sarcasm" sign for him). Not to mention, in one of the first episodes he's made to throw his dinner in the trash and proceeds to pick it back out moments later to eat as nothing happened. Compare this to his later self who won't even touch a used napkin or share a drinking glass without thinking he's doomed. Also, he swears now and then in the first season, but later shows an aversion to doing so, much like some children.
Similarly, Penny was a lot dumber initially (for example, claiming her screenplay isn't based on her life because she's from Omaha, not Lincoln). She quickly moved from The Ditz to Closer to Earth.
Bernadette originally was unable to understand jokes and sometimes even sarcasm, though this might be a bit of Character Development as she gradually started explaining when something was a joke. It's later implied she was simply Obfuscating Stupidity.
Stuart (the owner of the comic book store) started out less nerdy than his current self. He easily conversed with Penny, entertained her and managed to get a date with her, and they continued to date in which they had apparently gone so far as to make out and nearly sleep together. Later on, however, he's become much like Raj in that he can barely talk to an attractive girl without being rendered speechless or freaking out, and in general became a lot more awkward and shy. He also takes on some creepy traits; a woman who came into the store posted a review in which she said Stuart stared at her without blinking the entire time.
Amy Farah Fowler began as explicitly a genderflipped Sheldon, initially only going on a date with him to satisfy her mother's demands that she date at least once a year. Now she's frustrated by Sheldon's lack of emotional and sexual intimacy, and frequently hitting on Penny.
In most episodes, Penny is the token female, and as often as not, she acts the part. (Occasionally subverted, as when she kills cockroaches for the guys. In such situations, one or more of the guys will take on the role of The Chick.)
Raj often takes the role of The Chick, being the most emotionally sensitive one of the entire group.
Although she's a chick, Leslie Winkle is almost never The Chick. Whenever she makes an appearance, at least one of the guys turns into The Chick. She lampshades this when attempting a relationship with Leonard, "I believe you should take on the male role."
Cliffhanger Cop Out: The Season 4 finale and Season 5 opener, dealing with the ramifications of Raj and Penny waking up in bed together. At the Comic-Con panel over the summer Bill Prady said they had worked out a solution that should make everyone happy, which ended up being Raj revealed to Penny that they didn't have sex because he was done when trying to put the condom on and instead just fell asleep.
Again during the season 9 cliffhanger and the season 10 opener. Sheldon's mom and Leonard's father didn't sleep together. It felt like another ratings stunt.
Cloning Blues: In the (fictional) B-MovieSerial Ape-ist 2: Monkey See, Monkey Kill Penny plays a clone of her character from the original film. She has problems though. The human DNA of the original character got mixed with the DNA of the Killer Gorilla that killed her. So she is more of a Beast Man than an actual human. Further anguish is caused by the killer urges she inherited from the gorilla.
Almost any of the female characters who appear on the show, but Penny most of all.
Also, Leonard compared with the other guys.
Most female characters are Closer to Earth than the four guys. Leslie Winkle, however, is more on a par with Wolowitz, Koothrappali and all the other 'average' nerds. Which makes her Closer to Earth than Sheldon, but much further from Earth than Leonard.
And then there's Amy, who is about as far out as Sheldon.
Closet Geek: Penny's primary interests at the start of the series was reality shows and fashion, but increasingly becomes this as the series progresses.
She saw the new '09 Star Trek movie alone and of her own accord while the guys were away in the Arctic.
Sheldon introduces Penny to MMO gaming, and Penny quickly becomes more addicted than any of the guys are.
She learns a few basics of science, although nothing significant. She turns to Sheldon to teach her at least basic physics so she can understand Leonard better and learns how to say some fancy terms but that was about it.
A late Season 6 episode has Leonard introduce her to Buffy the Vampire Slayer. She seems to enjoy it but Leonard is disappointed that she's not obsessed with it like he thought she would be. She has a mild personal crisis in realizing she doesn't have the same passion for these things that they do.
She watched a lot of Doctor Who with Leonard and in one episode reveals she knows the mythology rather well. In the same episode, she freely admits loving Game of Thrones of her own accord because "there are dragons and people doing it."
Cloudcuckoolander: Raj is a bit like this, and the trait seems to be more prominent in more recent episodes.
Sheldon is basically on another planet as far as social norms are concerned.
It's revealed in "The Werewolf Transformation" that Sheldon believes that barbers keep "haircut records."
Somewhat Truth in Television. Many hairdressers keep records of what color dye they've used on a customer and some also note in which style they cut the hair. Though when you're like Sheldon and you get the exact same cut every time it's probably a lot less likely.
The Cloudcuckoolander Was Right: In the episode where the university has asked the male characters to come up with ideas on how to improve recruitment of women to graduate-level science and engineering programs, Sheldon of all people has arguably the best approach: start the process early, with middle-school girls (so that they'll gain the right preparation in high school to pursue undergraduate science degrees and therefore be in position to enter graduate science programs). When Leonard, Howard, and Raj make a mess of the project by alienating the class they're speaking to, Sheldon rescues things by bringing Amy and Bernadette in via speakerphone to address the class as female role models in the sciences.
After Sheldon ends up charming Raj's date (a successful dentist) causing her to leave for the date with him instead, he then completely fails to understand why he would see her again? He already has a dentist!
The Cobbler's Children Have No Shoes: Leonard's mother Beverly is a professional psychiatrist, but she has a very distant and unemotional relationship with her own children, having apparently treated them more like long-term test subjects than a family.
Cold Open: Every episode, although some use the rotating electron diagram and whoosh noise before starting.
Howard driving the Mars Rover into a ditch in an attempt to impress his date.
Some of Howard's anecdotes include this trope. For example, he was once maced by one of his "seductees". Whilst it is possible that the girl in question was overreacting (she probably has to be to keep Howard on the sunny side of the Moral Event Horizon), Howard must have been doing something very wrong for that to happen in the first place.
After Bawwy Kwipke humiliates him on national radio, Sheldon's first thought is to murder him. Although he only briefly discusses it with the others (he notes that there are several neurotoxins that would "leave no trace") before being talked out of it, the speed at which his mind works would suggest that he had actually advanced quite far in his mental planning.
Sheldon at one point seriously suggests using negative reinforcement, specifically electric shocks, to change the register of Penny's voice. Don't annoy Sheldon or he'll torture you into better behavior.
If one subscribes to the theory that Sheldon is on the autistic spectrum, Penny's systematic disruption of his carefully ordered life during their Escalating War falls firmly into this trope.
In an episode, where Penny dates Leonard's colleague, David Underhill, and he is jealous:
Leonard: You said that you didn't want to go out with me because I was too smart for you! Well, news flash, lady, David Underhill is ten times smarter than me! Penny: Dave is not smarter than you. He's an idiot. Leonard: Really? Why would you say that? Penny: Because a smart guy takes the nude photos of his wife off his cell phone before he tries to take nude photos of his girlfriend. Leonard: You let him take nude photos of you? Penny:That's what you took from that?! The guy is married!
After Sheldon gets home after taking off with Raj's date Lalita (a dentist), Leonard asks him if he's going to see her again. Sheldon is puzzled and remarks that he has no reason to because he already has a dentist. The icing on the cake is Sheldon shooting Leonard a look as if it's Leonard who is missing the point.
One of Sheldon's ongoing gags is that despite his genius I.Q., he is completely clueless about being social, leading to many missed points.
Leonard: You convinced me. Maybe tonight we should sneak in and shampoo her carpet.
Sheldon: You don't think that crosses the line?
Leonard: Yes... For God's sake, Sheldon, do I have to hold up a sarcasm sign every time I open my mouth?
Sheldon: You have a sarcasm sign?
On his first date with Emily, a deaf acquaintance of Penny's, Raj is trying to think of things to say, and Howard is translating for him.
Raj: I love music. Do you love music?
Howard: You really wanna ask her that?
Raj: Oh, you're right. Everyone loves music.
Sheldon with most social interaction, but a notable example that doesn't quite fit into that category:
Sheldon's Date: So, Flatland is not only a mathematical essay, but also a treatise on the social mores of Victorian England. Sheldon: You know, I never considered that! That is going to completely change my visits there.
A hurricane of them in "The Plimpton Situation", when Leonard tries to hint to Howard and Raj that he was up all night with the titular scientist.
Sheldon considers A Beautiful Mind to be a "wonderful romp" of a movie. One can infer that because John Forbes Nash won the Nobel Prize and revolutionized game theory, Sheldon has utterly overlooked the fact that the film is actually about Nash's struggle with a severe mental illness.
From "The Large Hadron Collision", in re Leonard choosing to take Penny to Switzerland on Valentine's Day to see the CERN supercollider instead of Sheldon.
SHELDON: "What? That's absurd. Penny has no interest in subatomic particle research."
LEONARD: "Yes, but it'll be Valentines Day. We can go sightseeing and skiing and make love in front of a roaring fire in the shadow of the snowcapped Alps."
SHELDON: "But Penny has no interest in subatomic particle research."
In "The Engagement Reaction" When Bernadette finds out the real reason why Howard's mother was in the hospital she chews him out for it. (He didn't know until she told her.) When she is asked where she is going she responds back with the following lines, everybody but Howard is surprised that she sounds like Mrs. Wolowitz when she shouts.
Howard: Where are you going sweetheart? Bernadette:[Wolowitz voice] TO THE TOILET!!!! IS THAT OK WITH YOU?!! [everyone but Howard reacts in surprise] Howard: Is it me or does she sound sexy when she's angry?
Penny has this problem in regards to her relationship with Leonard. The couple eventually works through it by Leonard putting the power to propose marriage in Penny's hands, so she won't have the weight of it on her shoulders until she decides she's ready.
Sheldon struggles with committing to Amy and then from there moving forward in their relationship. In his case, the issue stems from having previously thought of himself as a Celibate Eccentric Genius who is above time wasting romantic notions, and having an aversion to change. In one episode both Leonard and Amy decide to move too fast for their partners and put moving in on the table. Sheldon and Penny are forced to confide their hesitations about it to each other.
Sheldon's explanation for "his spot" on the couch used in the pilot is repeated at several other times, once verbatim by Penny when Bernadette first joins the group. In the flashback in late Season 3, Sheldon's explanation for his original spot, using a lawn chair, was identical except that it discouraged communication in a group, reflecting how far he had come socially.
Other nods are used as brief moments, one in particular being when Howard crashed the Mars Rover and Sheldon confessing the act being the reason Howard loses security clearance on a new project.
One episode involves Sheldon going to court due to his bad driving when helping Penny in "The Adhesive Duck Deficiency".
The first episode mentions Joyce Kim and the transvestite neighbor, who both show up in the flashback episode.
The episode "The Hawking Excitation" mentions Sheldon's restraining orders from Leonard Nimoy and Stan Lee.
After buying a replica of Longclaw in "The Russian Rocket Reaction" it's shown from thereafter to be hung up on the wall of the apartment.
The Convention Conundrum: Sheldon mentions he can't legally contact Leonard Nimoy, Stan Lee and Bill Nye. This is due to the above mention restraining orders including the most recent one filed by Bill Nye.
Amy is seen in this episode, wearing the tiara that Sheldon gave her as an apology.
Competition Freak: Bernadette is extremely competitive. As Leonard discovers in the scavenger hunt.
Contralto of Danger: Bernadette usually has an adorably squeaky voice... until she gets pissed off. Then her voice drops low and the other characters know she means business.
Cool Big Sis: Penny ends up being like this to the others, (despite being younger) a normal person who helps them with fashion and relationship issues, lampshaded with a discussion with Sheldon where this is played more literally when she talks him into letting her cut his hair.
Cool Loser: Thoroughly averted. While they have their own tight group of friends, they all have quirky mannerisms that would likely make them a bullying target, especially Sheldon. Leonard is the most normal and friendly of the group but especially in the early seasons he has an almost painfully timid disposition. This is a stark contrast to other stories that either have "charmingly geeky" main characters or the "awkwardly geeky" characters as only secondary characters.
It also helped that they had an actual woman as Wonder Woman, and a guy "that actually has muscles" as Superman.
"The Holographic Excitation": The newly weds Howard and Bernadette are both small people (as in short and thin), so they dressed as a couple of cute smurfs for a Halloween party.
"The Holographic Excitation": Amy and Sheldon are going to a Halloween party and she tries to convince him to wear couple costumes. Amy wants something romantic that shows everyone that they together, while Sheldon doesn't understand the sentiment and would prefer Star Wars characters R2D2 and C3PO, or Hewlett and Packard, founders of the HP company. Their compromise is being dressed as Raggedy Ann and "Raggedy" C3PO.
Sheldon: It was a compromise. I lost.
"The Imitation Perturbation": For Leonard and Penny's Halloween party, Howard and Bernadette go as Bert and Mary Poppins, while Raj and Anu go as Supreme Court judge Ruth Bader Ginsberg and the U.S. Constitution. Sheldon and Amy were going as Doc Brown and Clara Clayton, but instead they go as Howard and Bernadette as payback for Howard dressing as Sheldon earlier.
In one episode they all dress like The Flash for Penny's Halloween episode.
Raj: "What if we all stood in different positions and looked like one guy running really fast?"
The episode "The Barkersfield expedition" opens with Sheldon steaming his Data cosplay and Leonard having to borrow make-up from his girlfriend for his. The A plot of the episode actually revolves around the guys getting stranded in the desert after pulling over on the way to ComicCon to do a full cosplay photo shoot. Leonard was dressed as Captain Picard, Raj as Worf and Howard as a Borg. They looked awesome.
In one episode, the girls decide to go to Disneyland and they buy Disney Princess line-up with costume, make-up, hairdo... The only problem was that they all wanted to be Cinderella. Bernadette claimed it was her idea and that she was the driver, so she won. Penny was Aurora and Amy was Snow White. Howard and Leonard really fancied their wife and girlfriend in their outfits.
Costume-Test Montage: Penny takes Sheldon to get a new suit that should give him confidence for his awards banquet.
Sheldon: (wearing an all-white, long tailed, frilly collared tuxedo) [when Penny says "no"] Okay, but anything I put on now is only going to suffer in comparison. [next shot of Sheldon wearing a classy, sharp black-on-black suit] This is absurd, I look like a clown.
The Couch: Leonard and Sheldon's couch in their apartment.
*Cough* Snark *Cough*: As Sheldon tries to explain to Amy that he is not losing his mind over her in "The Zazzy Substitution", Leonard then employs this trope to prove otherwise.
Amy: Your mother thinks you might be losing your mind over me. As a neurobiologist, I was curious. Sheldon: Well, your curiosity is unfounded, as I am in full possession of my mental faculties. Leonard:(pretending to sneeze) 25 cats! Mary Cooper: Oh, God bless you, dear.
Cow Tools: You could spend forever looking at Leonard and Sheldon's apartment and the comic book store and see all sorts of geeky collectibles. You can also make out computer manuals and software cases in their bookshelves. One especially interesting device is an antique fuse holder hanging by the back hallway.
Crazy Cat Man: Briefly. After a falling out with Amy in which he terminated his relationship with her, Sheldon buys 25 cats.
Sheldon: I have a pre-packed emergency 48 hour survival kit recommended by the Department of Homeland Security... and Sarah Connor.
Sheldon also stages Emergency Disaster Drills every three months for every possible event from floods and earthquakes to Canada invading California.
In anticipation for a Scavenger Hunt / Treasure Hunt in "The Scavenger Vortex," Sheldon brings his bowling ball along on the offhand chance the clues lead them to a bowling alley (being germophobic and hating using rented balls). The bowling ball in his backpack slowing him down is brought up several times, but he was correct in that one clue was at a bowling alley. Brandishing his ball in the car, he exclaims "My brain is better than EVERYONE'S!"
Credits Gag / Freeze-Frame Bonus: The Chuck Lorre Productions logo and ensuing paragraph at the end of every show. Sometimes manages to get away with things the show probably wouldn't by virtue of the fact that nobody sees them on TV anyway. A complete list of them can be found here.
For example, the one at the end of the Age of Conan episode details Lorre's recent trip to Vegas and his imagining of a man going home and "blowing his brains out" after reflecting on his unsatisfying job.
Sometimes CBS' radar still manages to catch them, and they're blanked out when they actually air (but not on Lorre's web site).
Freeze-Frame Bonus also applies to the opening credits. Among other things, there is a TTC subway train, a 3-1/2" floppy disk, a disco ball, and a Hollywood Ave. street sign.
Creepy Gym Coach: In one episode, Penny mentions passing gym due to the affections of her (female) coach. In another, Sheldon mentions running from his own coach who was obsessed with taking his temperature with a rectal thermometer.
Creepy Stalker Van: Alluded to when the guys decide to start their own comic book shop. One of the guys says that when he was growing up, he couldn't get to the local comic book shop and suggests they get a van to pick up local kids and bring them there. Only Leonard realizes the implications.
Cultural Rebel: Rajesh is not too fond of Indian food, while Howard takes a perverse thrill from not keeping kosher.
Raj also can't seem to stand the idea of going home.
"I don't want to go back to India! It's hot, and it's loud, and there are so many people. You have no idea, they're everywhere!"
Raj and Howard go back and forth on their respective cultures, as noted by Penny when predicting the guys' orders at The Cheesecake Factory in "The Panty Pinata Polarization"
"Shrimp Caesar salad with no almonds for the highly allergic kosher-only-on-the-high-holidays Howard, and for our suddenly-back-on-the-Hindu-wagon Raj, meat lovers pizza, no meat."
Sheldon is also one regarding his mother's religious lifestyle. He resents that he was forced to go through Cotillion, pointing out the lack of application that having all the social graces to be able to function in 18th Century Vienna presents.
Sheldon also affects an more upper-class accent, only slipping into his native Texan drawl when flabbergasted, irritated or angry.
Cute Bruiser: You don't wanna wind up in a situation where Penny's fist meets your face.
Also Bernadette studies Krav Maga.
Cute Kitten: Sheldon's favorite childhood lullaby "Soft Kitty" proves you don't even need an actual kitten for this trope.
Sheldon does not, however, enjoy LOLCats; an email of such from Penny gave her her first strike.
Sheldon's 25 cats. Especially Zazzles, he's so "Zazzy".
Cute Mute: Emily, a deaf girl that Raj dates. Subverted when she turns out to be a gold digger, which is not so cute.
Cutting the Knot: Penny has to get Sheldon's flash drive from inside a puzzle box. Before he gives her the instructions on how to open it over the phone, Penny asks if he has any emotional attachment to the box. When Sheldon answers no, she simply smashes it open.
In another episode, Howard tries using a robot hand to pleasure himself. After Leonard and Rajesh run out of ideas of what to do, they take Howard to the emergency room. There, the nurse suggests simply restarting the computer attached to the hand, and despite Howard's pleas not to do so, she turns it off, and the hand lets go.
Darwinist Desire: Sheldon tries to find which of his friends is the best genetic match for his sister, on the hope that the offspring might be a genius like him. When she finds out, she lets her feelings be known to Sheldon...by kneeing him in the groin.
When Leonard wonders how he can date someone who believes in psychics, Howard draws a diagram showing how few women will share his views, like him and be liked by him. When Leonard complains, Howard draws a dot on Leonard's palm.
Leonard: What's that?
Howard: Your new girlfriend. You two have fun tonight.
Subverted in The Love Car Displacement: We see Raj, alone in his room, cheerfully step out of the bathroom with a box of tissues. He grabs two tissues and gets under the covers, shivers with anticipation and turns on the TV.
Announcer: Next on Turner Classic Movies: Bridget Jones Diary. Raj: (sniffing) Oh God, Im crying already.
Female example with Amy:
Amy: And if the bar doesn't work out, we can always go to Walgreen's and get you a nice electric toothbrush. I call mine Gerard.
Leonard muses that it's wonderful his girlfriend is 9000 miles away; he can do anything he wants.
Howard: You mean playing D&D with us then taking a suspiciously long shower?
Amy once again in "The Werewolf Transformation", musing on Sheldon growing his hair out.
Amy: I think you might look sexy with long hair. Be the kind that flows down to your shoulders and blows back while riding on a horse. Bareback and barechested... I-I'm going to go brushmyteeth, it might take a while.
Howard also took on this attribute more in later seasons.
The entire cast takes turns with this.
This is basically all Leonard does now since he got with Penny.
Just about anybody who has to deal with Sheldon becomes this at some point.
Sheldon was supposed to be this for Leonard in the pilot, but became a Breakout Character and was delegated to Butt-Monkey instead. He still has moments of this, though it's mostly unintentional as he usually doesn't understand sarcasm.
Penny did this to Raj in "The Skank Reflex Analysis."
Bernadette took this trope Up to Eleven in the same episode.
Death Ray: Sheldon's mother or Sheldon has mentioned that Sheldon tried to build one as a kid but failed and thus they kept teasing him.
Pissed the dog off something terrible though.
Sheldon ended up building a 'death ray' to scare off a bird that tormented him. As it was dubbed this by Howard, Sheldon corrects him, and then goes on to say that if he DID have a death ray, he'd be in his lair enjoying the money the world gave him for not using it.
Leonard: Sometimes your movements are so lifelike, I forget you're not a real boy.
Defcon Five: Leonard falls victim to this trope and is then lectured by Sheldon.
Defenestrate and Berate: When Penny finds out that her boyfriend writes a blog about their sex life, she violently breaks up with him. She storms to the guys' apartment, opens the window and throws out her soon-to-be ex's iPod and calls him a jerk.
Definite Article Title: With the exception of the pilot, all episode titles are in this form. In general mimicking the names of scientific principles and making a reference to the events or dialogue of the episode. Starting with The Big Bran Hypothesis (episode 2), and continuing with The Fuzzy Boots Corollary (episode 3), etc.
Defrosting Ice Queen: Amy started as a Distaff Counterpart to Sheldon but has received Character Development into a more energetic and outgoing person. This showed that her closed off personality is a result of years of emotional trauma and romantic rejection causing her to cope by suppressing that part of her and now she is experiencing the emotional growth that was denied her.
Delayed Reaction: When Penny says "I love you" to Leonard, it takes him, her, and the STUDIO AUDIENCE a second to react to the significance of her saying that.
Demand Overload: In universe. Penny starts a small business making hair barrettes called "Penny Blossoms." The guys set up a website for her and an order comes in for 1,000, rush overnight delivery. The guys help her out making them all night. Then after they're done they find that the original order has been doubled.
>Knockknockknock< "Penny!" >Knockknockknock< "Penny!" >Knockknockknock< "Penny!" -Sheldon, who has also knocked on other people's doors thusly.
Depending on the Writer: Sheldon's mechanical aptitude. In some episodes, we see him put together a sonic generator to scare off a bird, or reminisce about building a working CAT scan machine as a child. In others, he literally can't figure out how to open a toolbox without Howard's help.
Sheldon is often on the receiving end of these Looks, mostly from his roommate Leonard or Penny.
Amy got four Disapproving Looks simultaneously from Leonard, Penny, Raj, and Sheldon when they were all administering Bernadette and Howard's wedding together, and Amy said that she would be happy to be Bernadette's maid of honour again should their marriage fall apart.
Dismissive Kick: In "The Geology Elevation", Sheldon is jealous of Burt getting a MacArthur grant and tried to throw a rock to vent his anger. It fell on his foot, so in frustration he kicked it... thus hurting his other foot.
Disproportionate Retribution: Penny touched Sheldon's food while having her own full plate of food and nearly ate his because she was hungry. She then sat in his spot to take a stand. He responded by banishing her from his and Leonard's apartment. Her response was to not serve him at the cheesecake factory, and then imply that she messed with his food. His response was to not let her use his wifi anymore. When she ruined laundry night for him, Sheldon went too far and flung all of her laundry, including her underwear, outside on telephone poles. All of this escalating war stems from Sheldon's deranged responses to small mistakes from Penny.
Distaff Counterpart: Amy to Sheldon, for sheer longevity. Leonard's mom Beverly also possesses similar quirks, such as having a very particular way of having her tea.
Lucy to Raj? Or is she more of a female Stuart?
Distracted by the Sexy: Whenever a new pretty girl shows up. Sheldon is immune, and, on occasion, so is Leonard. Howard is always the first to lose focus. In fact, one time just hearing that Penny's visiting "friend" from Nebraska was easy meant that between shots, Howard somehow managed to literally disappear from the room!
Subverted when they are focused on something else and the Sexy is verbal. Once, Penny and three friends stop by while they are playing Halo and ask if they want to have an orgy. After no response, Penny tells her friends "I told you so," and they leave. Shortly after, Leonard pauses the game and says he thought he heard something, but he shrugs it off. On another occasion the four guys are trying to come up with a better way to set up her entertainment system than the way suggested in the instructions and Penny attempts to get their attention by announcing that she was going to take all her clothes off, to no response.
Once when Penny described a falling out with a recently acquired boyfriend.
Penny: A smart guy takes the nude photos of his wife off his cell phone before he tries to take nude photos of his girlfriend. Leonard:He tried to take nude photos of you? Penny: That's what you took from that?! ...The guy is married! Leonard: Oh yeah. I'm uh... oh, that's terrible!
Amy and Sheldon tried to do a social experiment to see which bits of juicy gossip would be passed quicker around their circle of friends. Being that they have little social skills, it was pretty obvious from the get-go their choice of subjects would render the experiment almost irrelevant.
Amy:(all in one breath) "Sheldon and I engaged in sexual intercourse. In other news, I'm thinking of starting an herb garden. Mum's the word. Gotta go."
Howard had admitted he really stops listening to Bernadette when she undressed, focusing more on her body than what she is saying.
Double Standard: Leonard learns about these the hard way—after Penny gets drunk and has meaningless sex with him, post-breakup, Leonard attempts to do the same, once with Leslie and once with Penny. They're not pleased.
Drama Queen: Debbie Wolowitz is this. If she's not bugging her son Howard dramatically, she's getting dramatic about something else.
Also, Sheldon. When even the tiniest thing goes wrong, or not even wrong but just not how he wants it, he acts like it's the end of the world.
Dream Sue: In "The Cooper Extraction", several What If? scenarios are depicted. The one narrated by Stuart is essentially a Fantasy Sequence, featuring a suave version of himself. In this scenario, Stuart is Penny's boyfriend. Fulfiling the needs of awkward and lonely Stuart to be someone better and to have a gorgeous girlfriend.
Drives Like Crazy: Penny does not actually drive badly, she drives like a person who has driven for a very long time and will sometimes bypass 'normal' behavior for a quicker route, such as not slowing down much over speed bumps. Her constant ignoring of the Check Engine light is a running gag, though.
Sheldon doesn't drive normally; part of the Roommate Agreement was that Leonard would take care of the driving. They eventually forced him to get a learner's permit but he will likely never get his license because even in a simulator he does horribly. In a later episode he had to drive Penny to hospital and while they got there in one piece, it wasn't a relaxing experience.
Driving Test: The gang try to teach Sheldon to drive using a computer simulation. He ends up driving through a virtual mall like in The Blues Brothers.
Leonard: Awww no, not the pet store!
Sheldon: Remind me to compliment Wolowitz on the software. The detail is remarkable.
Drop-In Character: Penny embodies this the most, as she has a tendency to stop by the guys' apartment for random reasons like coffee or tech support (Raj and Howard are usually over there for an actual activity like Halo night). On the other hand, Leonard often visits Penny in her apartment in not too dissimilar a manner, although often expressly because Penny needs someone to talk to. Penny does this so much that she will casually drop by the apartment in her sleep clothes, much to the displeasure of one of Leonard's girlfriends.
Dropped After the Pilot: In the unaired pilot there's a girl named Katie whom Leonard & Sheldon rescue from being homeless and moves in with them, and Gilda, geeky female friend/fellow researcher of theirs with whom Sheldon has had sex.
Dumbass Has a Point: Zack of all people comes out with one in "The Thanksgiving Decoupling" when Penny realises their "fake" Vegas wedding was real and is trying to get him to sign the annulment paperwork:
Zack: I dont know if I want to sign it.
Leonard: Why wont you sign it?
Zack: I just think splitting up can be rough on kids.
Penny: We dont have any kids.
'Zack: Are you sure? Cause you didnt know we were married until this morning.
Dumb Blonde: In the early seasons, Penny was flighty at times, but overall wasn't very stupid. The first couple of episodes she was more The Ditz but this was replaced with her generally being more Closer to Earth. Later on, she was Flanderized to fit this trope quite a bit more, being frequently thrown by easy to understand incidents (for example a simple, yet not short, sentence where the hardest concept was "joined ownership")
In one episode Penny takes some physics lessons from Sheldon so she could better understand Leonard and what he does. Although Sheldon is a horrible teacher, she does seem to learn a little, at least enough for a Technobabble gag.
Dumb Is Good: Averted by the majority of Penny's boyfriends, who are dim and often rather obnoxious. Fitting the Jerk Jock type. Played straight for Zack Johnson, one of her most prominent boyfriends. He is dimwitted but one of the friendliest and nicest characters ever depicted in the series. He ends up befriending the guys and even enjoys their hobbies.
Dung Fu: Amy Farrah-Fowler was briefly suspended from working with experimental primates for "unprofessional behaviour". During her studies in addiction in apes, her experimental animals, outraged at being deprived of cigarettes and alcohol, flung faeces at her. Amy ruefully accepted that flinging it back was probably not the most professional behaviour for a scientific researcher.
Early Installment Weirdness: Sheldon is a lot more relaxed in the pilot episode, and while droll he seemed mostly socially capable. Compare to the flashback to when Leonard moved in from Season 3, where Sheldon is much more socially awkward. He also borderline flirts with her and competes for Penny's attention, two things he completely stops afterwards. He also undermines Leonard about his chances with Penny but Penny isn't insulted; this reverses as they become friends. And he uses the phrase "have sex" instead of "engage in coitus."
Many early episodes display Sheldon without traits that later become trademark actions, such as knocking on Penny's door once instead of thrice, and without stopping to say her name.
The Rule of Three that later becomes part of Sheldon's Super OCD also gets skipped when Sheldon gets the flu and he calls out for Leonard only twice.
In "The Justice League Recombination" the guys have to apologize to Zach for making fun of him.
Sheldon: Milk Dud? Zach: Oh I LOVE Milk Duds! ...okay, we're cool.
Well, Milk Duds are the most apologetic of the boxed candies.
Eerie Arctic Research Station: The boys go to an Arctic station between seasons to conduct experiments. Spending months alone with Insufferable Genius Sheldon was too much for them, so they had to resort to falsifying data to keep him happy.
In another episode the guys team up to help Sheldon get over his fear of public speaking, comparing themselves to the X-Men. Sheldon thinks that "since I am Sheldon Cooper, you shall be my C-Men."
Egopolis: Sheldon's SimCity he designed, Sheldonopolis. With architecture including Sheldon Square, Sheldon tower, Sheldon Stadium (home of the Fighting Sheldons), and Shel-Mart.
Eldritch Abomination: Not a straight example, but the painting of Penny and Amy from "The Rothman Disintegration" is hilariously treated as though it is one, by both Penny and Bernadette.
There is also Howard's mother who though never clearly seen onscreen is described as an extremely obese, bald(ing) old woman who takes thirty minutes to climb three flights of stairs and needs help putting on dresses as she can't put her front and back in at the same time on her own.
Howard's mother: It's like tryin' to keep two dawgs in a bathtub!
Embarrassing Hobby: Sheldon Cooper goes to a cellar room in Caltech every day to play keepie-up with a beanbag. He tries to hide it from his friends and Hilarity Ensues when they try to find out what exactly Sheldon does in the half-hour he mysteriously takes every day.
Emotional Regression: Many of the characters are still fairly young at heart, so even though they are degree'd professionals they can sometimes act like kids, especially when put into uncomfortable situations. Sheldon is the most notable, being a Manchild on a fairly regular basis, but Leonard always becomes a kid when his mom comes to visit and Howard still has a mother/child relationship with his mother.
The Ending Changes Everything: The 100th Episode starts with Leonard and Sheldon climbing the stairs, and Leonard glances Penny with Amy and Bernadette in her apartment. He impulsively asks her out, which she accepts, and the rest of the episode is them exploring if they can be together again, which devolves into keeping their new relationship a secret arguments over miscommunication and defaulting to having sex to distract them from their problems. Leonard confesses that all scenarios that go through his head about them end badly, and she tells him he is always overthinking things. We then jump back into the original stairwell scene, as the entire episode was a daydream that happened in an instant the moment he saw Penny. He impulsively asks her out again, but this time she asks if he has thought this through and he replies "Yes, and I think we should go anyway."
Epic Fail: Exhibited by both Sheldon and Barry Kripke in their one-on-one basketball game to decide who gets the corner office in "The Rothman Disintegration." Leonard's comment while watching the "game" says it all:
Leonard: You know all those terrible things bullies used to do to us? I get it.
Basically how the producers described the first attempt at a pilot. The only thing that worked was Leonard and Sheldon's interaction, as well as Galecki and Parsons chemistry. The proto-Penny, Katie, was despised by the test audiences, as her relationship with the guys was reversed. Instead of being (generally) a bright ball of sunshine in their lives she was a manipulator and the guys would work to bring her out of her cynical outlook.
Between Raj and Sheldon in "The Hot Troll Deviation".
Between Penny and Sheldon when Penny finally had enough of Sheldon's insistent quirks, but it started largely because Penny got her "third strike" and Sheldon banished her from the apartment. Penny struck back by using up all the washing machines during Sheldon's laundry day, knowing how regimented his schedule is, but Sheldon has no boundaries he isn't willing to step over.
Between Howard and Sheldon in "The Parking Spot Escalation".
Escape Call: Played with. Howard wants the astronauts to nickname him Rocket Man, so he arranges to have Raj call him during a teleconference, with Elton John's "Rocket Man" as the ringtone. Unfortunately, they also hear Howard's mother call him down for breakfast, warning him that his Froot Loops are getting soggy. So Howard's astronaut nickname becomes Froot Loops.
Escort Distraction: In "The Peanut Reaction", Howard has to take Leonard out so the others can plan a birthday party for him. To do this, Howard fakes an allergic reaction so they have to go to the hospital, and when he can't hold Leonard away any longer, he incurs an actual allergic reaction by eating a candy bar with peanuts.
While Sheldon loves his mom he still dislikes her religious zealot personality and is fine with jokes at her expense. When it comes to his "Memaw" (Grandma) he absolutely adores her.
The Department of Homeland Security apparently has a plan in place for when Sheldon goes too far with his abilities. It involves telling his mother on him.
Even Beggars Won't Choose It: When looking through Leonard's wardrobe, Penny picks out several shirts and tells Leonard to throw them away, noting that he shouldn't even give them to charity because: "Seriously, you won't be helping anyone."
Everyone Is a Suspect: In "The Mommy Observation", Raj organizes "another classic Koothrappali murder mystery dinner". Stuart is the murder victim, murdered in a room where Leonard, Penny, Amy, and Bernadette were present. The premise is that they are all murder suspects.
Everyone Knows Morse: Subverted in the episode "The Cooper-Nowitzki Theorem". Sheldon attempts to use Morse code; however, Leonard claims he doesn't know Morse code and refuses to learn it at three in the morning
Embarrassing Tattoo: Penny has one she claims is the Chinese symbol for "Courage". According to Sheldon, it actually means "Soup".
Sheldon: But I suppose it does take courage to demonstrate that kind of commitment to soup.
Actually, the two symbols are pretty close / see here◊
Everyone Meets Everyone: The episode "The Staircase Implementation" is a Whole Episode Flashback. In it Leonard first meets Sheldon and moves in with him. Then he invites his friends Howard and Raj to visit the new apartment. Introducing them to Sheldon, when the latter comes home.
"Did you have to make me sound like a Simpsons character!"
You kind of have to agree with him about the cell phone voice recognition software.
Leonard: Let me try one! Calling Mcflono Mcfloonyloo!
Cell phone: Calling... Rajesh Koothrappali.
Rajesh: Impressive! ...and a little racist.
After Howard imitates the Bollywood Breakdance routine that Raj performed whilst heavily inebriated the night before:
Raj: That's very offensive.
Howard: Yeah, we thought so too.
This even applies when the potential racism isn't aimed at Indians:
Raj: Spiders give me the jeebie jeebies.
Howard: Its heebie jeebies.
Raj: I know, but that sounds anti-Semitic.
Everything's Better with Monkeys: Amy is shown owning a cigar-smoking capuchin monkey in the episode "The Agreement Dissection". Although, to quote her, he's a bit of an ass.
Evidence Scavenger Hunt: In "The Mommy Observation", Raj organizes a murder mystery dinner. Stuart plays the murder victim and everyone searches for the clues Raj planted.
Evil Counterpart: Late in the second season, a new neighbor moved in above Leonard and Sheldon, Alicia. She is pretty, blonde, an actress, and very quickly acquires the attention of the guys, much like when Penny moved in. The main difference is that Alicia was a shameless flirt and manipulated the guys to do everything for her. While Penny did many similar things, she generally treated them with respect and didn't abuse them. Partially out of jealousy and partially out of concern for her boys, Penny eventually clashes with Alicia.
Evil Genius: Sheldon occasionally invokes this on purpose (see Evil Gloating and Evil Laugh below). Leonard has already noted that Sheldon's "one lab accident away from becoming a supervillain".
Later, when Leonard states that he's worried about Sheldon, Howard says "So am I. I'm worried that one day, he'll set off a low-yield nuclear device because the cafeteria ran out of lime Jell-O."
Prof Proton (to Leonard) "Is he dangerous?"
Leonard "Actually, he's a genius"
Sheldon "I am!"
Prof Proton (to Leonard) "That doesn't answer my question...."
Evil Gloating: "Hello, Kripke. This classic prank has been brought to you by the malevolent mind of Sheldon Cooper."
Evil Cripple: No less a person than Professor Stephen Hawking (normally the cameo Genius Cripple) adopts the Evil Cripple persona, when he trolls Sheldon Cooper and Leonard Hofstadter with abusive critique of their science, just for the fun of it. As Sheldon and Leonard try to puzzle out who the stalking troll is, the camera pans to Hawking grinning and making mechanical cackling noises.
Evolving Credits: As of Season 6, Amy and Bernadette have been added to the open.
Exposition Already Covered: In Season 4 "The Toast Derivation", everyone except Sheldon is gathered at Raj's apartment for dinner, and someone proposes a toast. They then tell Raj's sister Priya that if Sheldon were present, he would talk about why it's called a toast (because of an ancient Roman tradition), even though they all know that, because it's just one of his quirks. Later, when Sheldon joins them, he starts to explain that very fact to Priya only to have her preempt him by repeating what the others have told her, much to his dismay.
Expospeak Gag: Sheldon's "I'm polymerized tree sap and you're an inorganic adhesive, so whatever verbal projectile you launch in my direction is reflected off of me, returns to its original trajectory and adheres to you." And this is just one of many instances.
Sheldon's attempt at 'trash talk': "I am given to understand that you mother is rather overweight. Of course, if this is the result of a glandular problem and not over-eating, I will gladly retract my statement."
Not to mention this gem from "The Desperation Emanation":
Leonard: What would you be if you were attached to another object by an inclined plane, wrapped helically around an axis? Sheldon: Screwed. Leonard: There you go.
Expy: (In Universe) When The Science Guy meets Professor Proton.
Bill Nye The Science Guy: Wow it is indeed an honor to meet you, Mr Jeffries. Without you I wouldn't have had a show.
Arthur 'Prof. Proton' Jeffries: Yeah, I know, that's what I told my lawyers!