Raj's long long slow and long hallway walk after trying to ask out Sheldon's sister. Actually, Raj's character is unto himself pretty hilarious.
The whole time machine acting-out segment.
In the same episode, at the end, Sheldon's Dream Within a Dream in which he uses the time machine to travel to the future and gets eaten by Morlocks starts out as Nightmare Fuel, but quickly Crosses the Line Twice when he tells Leonard he needs to move it out. The moving company workers turn out to be Morlocks.
Leonard hearing a noise and coming out of his bedroom with a lightsaber.
The end of the Physics Bowl. "Here I am, janitor. In former Soviet Union, I am physicist. Leningrad Politeknika. Go Polar Bears."
Sheldon's reaction when, after he gets fired from work, Leonard calls his mother to snap him out of his obessive funk. Watching him mouth the words "YOU CALLED MY MOTHER?" silently with a very offended look on his face is priceless.
When Leonard, Sheldon, Howard, and Raj all end up almost going as The Flash. And the series of "Oh no!"-s during said scene.
Leonard: I call Frodo!
Sheldon: "Ah gravity, thou art a heartless bitch."
One of Leonard and Sheldon's first meetings with Penny:
Leonard (staring after Penny after she's left): "Our children will be smart and beautiful."
Sheldon: "Not to mention imaginary."
Season Two
In one episode, Leonard comes back from a date with Penny and discovers that Howard and Raj were watching him say goodbye to her on a surveillance camera, which leads to this:
"I possess the DNA of Leonard Nimoy?! I can GROW MY OWN LEONARD NIMOY?!?"
Penny uses a very geeky simile:
Penny: Leonard and Howard and Raj aren't like other guys. They're special. How can I explain this? They don't know how to use their shields.
Alicia: Their shields?
Penny: Like in Star Trek, when you go into battle, you raise the shields. (stunned pause as she realized what she said) Where the hell did that come from?
Sheldon's money is hidden in the hollowed out buttocks of an action figure, whose identity will remain secret for his own protection.
But if you ever find yourself short, there's always a couple of twenties in Green Lantern's {[ass|Shove}}.
The first episode with Leonard's mother, Raj and Howard were teasing Leonard about all sorts of childhood issues. Leonard got back at them by directing his mother's psychoanalyst nature at them. Her conclusion of Raj and Howard being in an "ErsatzHomosexual Relationship" leaves the two almost catatonically stunned silent (Raj even more so) and Leonard's victorious smile/Troll face just making the scene.
Penny screwing with Sheldon as he does his knocking routine in the season finale:
Sheldon: *knock knock knock* Penny?
Penny: *knock knock knock* Sheldon?
*Sheldon looks puzzled*
Sheldon: *knock knock knock* Penny?
Penny: *knock knock knock* Sheldon?
This goes back and forth, faster and faster each time, culminating in Penny finally opening the door wearing a mischievous smile on her face.
Sheldon's Southern accent.
"Sure, why not! And after the sun's down, we can all pile in my pick-up and go skinny-dippin' down at the crick. 'Cause today's the day to STOP MAKING SENSE!"
"Here, drink-slash-eat this [a stick of butter in a cup of hot cocoa]."
"The Ballad of Leonard Hofstadter", sung by Sheldon, after Leonard gets Penny's ex, Kurt, to pay back the money he owes her.
Sheldon: *Sings* There once was a brave lad named Leonard, with a fi-fi-fiddle-dee-dee. He faced a fearsome giant, while Raj just wanted to pee.
One of the rare occasions where an incredibly funny moment is also a Tear Jerker: After Leonard reveals he built a hugging machine to use on himself as a kid, due to his mother giving him no affection at all, he also notes his dad used to borrow it very often!
Penny accidentally shoots Sheldon's "spot" on the couch with a paintball gun...after attempts to clean it up go wrong, Penny tries to solve the problem by turning the cushion over. Leonard notes there's no "butt-print" so Penny sits in the spot. In a great bit of Comically Missing the Point:
Leonard: It's too small and too...perfect.
Penny(grinning): ...THANK YOU!
Leonard(also grinning): You're welcome...
The response by Leonard(and later the other three guys) when asked if he remembers Kurt(Penny's ex-boyfriend): Holding a hand way above his head to indicate how big he is.
Raj: Ha-ha! Eat my dust, racially stereotypical plumber. (The race ends and Raj wins.)
Sheldon: That's not fair! I got stuck behind a tree.
Raj: And a cow, and a penguin. Face it, dude, whether it's a real car or a virtual cartoon car, you can't drive.
Sheldon: I just need a little more practice.
Raj: What you need is cheat codes, motor skills, and a magic genie who grants wishes to little boys who suck at Mario Kart.
Sheldon tries to teach Penny physics, but ends up only confusing her (Penny is revealed to have never taken a science class before). At last, a very confused Penny breaks down in tears, resulting in this exchange:
Sheldon: "Why are you crying?"
Penny:(exasperated) "BECAUSE I'M STUPID!"
Sheldon: "Well, that's no reason to cry. One cries because one is sad. For example, I cry because others are stupid and it makes me sad."
Raj in a bad mood:
Leonard: "I've always been a little confused about this... why don't Hindus eat beef?" Raj: "We believe cows are gods." Sheldon: "Not technically. In Hinduism, cattle are thought to be like gods." Raj: "Do not tell me about my own culture, Sheldon! In the mood I'm in, I'll take you out, I swear to cow!"
Sheldon gets a summons due to a traffic fine he got helping Penny out when she dislocated her shoulder in the shower, Sheldon denies any wrongdoing, meanwhile, Raj has been wearing a sound effect T-Shirt and playing sound effects the whole episode.
Sheldon: I'm not going to pay a fine, that would imply I'm guilty!
Howard: But you are guilty.
*Raj plays the Law & Order "Dun Dun" sound effect, which everyone laughs at*
Leonard: Here's Spock's head with no body. Here's Mr T's body with no head. Ah, here it is, Spock's body with Mr T's head! "I pity the fool who's illogical!"
Stuart's crowning moment of sadness describing the 'big night' he has planned- sharing a tin of tuna with a cat he doesn't own that may or may not stand him up.
Sheldon's attempt at trash-talking along with Stuart's deadpan reaction:
Sheldon: You bowl like your mama. Unless, of course, she bowls well. In which case, you bowl nothing like her.
Stuart: Oh. Ouch.
Season Four
The entirety of "The Robotic Manipulation".
Raj: You slipped and fell into a robot hand? Howard: Yes. Raj: Penis first? Howard: Yes, now help me! Leonard: I'd suggest a lubricant, but I have a feeling you fell on some of that as well.
Nurse: I need an orderly with a wheelchair, I've got a robot hand grasping a man's penis out here.
Howard: Do you think you could be a little more discrete?
Nurse: I'm sorry. We don't have a code for "robot hand grasping a man's penis."
Howard trolling Raj:
Penny: How does (Raj) know I jog?
Howard: Oh, he watches you from his car with high-powered binoculars.
(Raj's eyes widen)
Penny: Oh, my God! That is so creepy!
Howard: I KNOW!
(Raj whispers in Howard's ear)
Howard: Oh, and he says he's not gonna stop.
(Raj's eyes widen again and he whispers in Howard's ear again)
Howard: Then see a shrink and figure out how to talk to women!
Howard's mood-setting preliminaries to A Date with Rosie Palms in 'The Hot Troll Deviation' including easy listening music, fancy footwork and ambient lighting (courtesy of crossed lightsabers hung above his bed).
Sheldon's reaction to Amy asking him to meet her mother is quite frankly hysterical, as he politely says he'd love to, turns off the webcam... and then runs down the stairs in a wild panic calling for Leonard to help him!
Sheldon's 25 cats!
Sheldon and Amy pretending to be in a actual relationship on a video call with Amy's mother.
"Time to make love to your daughter's vagina."
Sheldon and Amy's experiment on memetics throughout "The Herb Garden Germination", where in reaction to gossip of impending break up between Howard and Bernadette led to them getting engaged ended that scene with this particular gem:
Sheldon: "Perhaps your talk of my sexual prowess renewed her faith in love."
Emphasis on the fact that it's SHELDON saying that.
The way Amy tries to spread rumors.
Amy: Sheldon and I engaged in sexual intercourse, in other news, I'm starting an herb garden, mum's the word, gotta go! *leaves*
Plus this little gem between Penny and a completely plastered Raj:
Penny: Sheldon and Amy had sex!
Raj: Shut your ass.
The ending.
Amy:(at Penny's door) I'm carrying Sheldon's child, mum's the word, bye!
(she walks down the stairs, and bumps into Leonard at the bottom, who has his cell phone in hand)
Leonard: YOU'RE PREGNANT?!
"Sometimes your movements are so lifelike, I forget you're not a real boy."
"The Toast Derivation" revealed that Sheldon once got punched by Bill Gates for saying: "Maybe if you weren't so distracted by sick children in Africa, you could have put a little more thought into Windows Vista."
Pretty much all of the Sheldon storyline with his group of new friends consisting of Barry Kripke, Zac and Stuart starting with their introductions 'Hello, my name's Stuart and what I'm most hoping to get out of this evening is a hot shower', a duet by Zac and Kripke of 'Don't go bweaking my heawt' and culminating with them plus Stuart (in a towel) singing "Walking on sunshine"note And proving, once and for all, why none of them ever embarked on a singing career.
Sheldon's Imagine Spot where after Leonard asks if he can change the temperature settings on the thermostat, Sheldon imagines himself as The Flash, running to the Grand Canyon, screaming and running back to Pasadena.
And Howard's Batman voice, especially when Penny punches him in the arm.
Howard: [whiny] Ow! ... I mean, [Batman voice] Ow.
Raj's Aquaman costume complete with integral seahorse- 'I've said it before... Aquaman sucks!'
In "The Agreement Dissection," Amy (drunkenly) offers to have her pet monkey assassinate Priya for Sheldon:
"If I can train a monkey to smoke, I can sure as Hell train him to shoot a poison blowdart, and no jury would convict us because PEOPLE LOVE MONKEYS!"
In the fourth season finale, Penny finds herself waking up in the morning in the same bed as Raj. Freaked out she insists that they completely forget that anything happened. Raj nods silently in agreement, having sobered up since last night. Penny asks incredulously "Really... still can't talk to me?!"
Any time Leonard's mom shows up. Especially when she mentions Howard and Raj's "latent homosexual tendencies".
When Sheldon thinks that Amy wants to take their relationship to the next level, he changes his and Leonard's address:
Sheldon: Oh, I explained my predicament to our letter-carrier. His exact words were "I gotcher back, Jack. Bitches be crazy."
In the fourth season finale, when Raj is Sheldon's temporary roommate:
Penny: What happened to Leonard?
Sheldon: The same thing that happened to Homo erectus: he was replaced by a superior model.
From the same episode, same scene: "I don't have an urge to fling my waste."
When Penny and Priya are finished with the longest, most awkward stair-climb ever, Priya goes into Leonard's apartment and Penny, unlocking her door looks back and says, "Amy was right. I do wanna fling my poo at her".
The second-to-last scene of "The Love Car Displacement": The episode had been full of growing tension between the characters and it all comes to a head in a Q&A panel at which the scientists in the group (and their friend Howard) are giving a presentation, with Penny in the audience. The scene is here. *
All you really need to know about the episode if you haven't seen it is that Howard and Bernadette got into a lover's spat over her enormous ex-boyfriend, and Raj cock-blocked Leonard.
Penny's reaction to a disheveled Leonard returning home in "The Benefactor Factor": She gives him a knowing smile, greets him with "Good morning, slut", and confirms that she knows the "walk of shame" when she sees it...
At the end of the episode, the whole cafeteria gives an embarrassed Leonard a standing ovation...and as the scene fades out, you hear one last line:
Howard: How was she?
In "The Desperation Emanation", Amy asks Sheldon to be presented to her mother as her boyfriend. Sheldon asks Leonard what to do. This leads to this exchange:
Leonard: Let me see if I can explain your situation using physics. What would you be if you were attached to another object by an inclined plane wrapped helically around an axis?''"
Sheldon: Screwed.
When Howard tells Leonard that he's getting back together with Bernadette:
Howard: I think I’m gonna take her to miniature golf.
Leonard: Ah. Well, I guess for you guys that’s like regular golf.
Leonard's "what the hell" expression as he watches sells it.
After Sheldon got himself purposely slaughtered in paintball due to his incompetence as a leader, it ended up inspiring the rest of his friends to take back the game. "If there is going to be a Church of Sheldon, this is where it began."
Made even better by exactly how he gets himself slaughtered. "Geology isn't a real science!"
Sheldon's "Look everyone! Wil Wheaton is my friend!" Followed shortly by "Brent Spiner, you are now my mortal enemy."
In "The Good Guy Fluctuation", after being the victim of many pranks throughout the episode, Sheldon finally gets his payback on Leonard in a big way when he springs out of the couch in zombie makeup.
Sheldon: Bazinga, punk. Now we're even.
From the same episode.
Sheldon: It's me, Sheldon, Mrs. Wolowitz.
Howard: That's not my mom. It's Bernadette.
Sheldon: Really? That's very unsettling.
This is topped moments later when Sheldon, forgetting the Electric Joybuzzer he's wearing, performs a Face Palm after getting pranked again.
Sheldon: Oh, how could I be so stuUuUuUuUuUuUuUuUuUuU- *falls over*
Sheldon's reaction to seeing the bluejay sitting in his spot in "The Ornithophobia Diffusion".
Penny: "Maybe she would like to know that half of your dirty movies... are animated!"
After Bernadette catches the bird, Sheldon tells her to carefully "flush it down the toilet".
Sheldon unveiling the Relationship Agreement to Amy, codifying the responsibilities of Sheldon Lee Cooper (known as "the boyfriend") and Amy Farrah Fowler (known as "the girlfriend"). Not only is it completely in character for Sheldon, but Amy is visibly moved by the whole ordeal (Mayim Bialik hits just the right tone between deadpan and getting choked up).
Amy: "It's so romantic!" Sheldon: "Mutual indemnification always is."
There's an extra layer in that scene, depending on when Sheldon drafted the Relationship Agreement. If he did it after getting confirmation from Amy to be his girlfriend, then he drafted a 31-page paper in the less than two hours, making it a C Mo A. If he did it before he asked Amy, then he wanted her to be his girlfriend for quite some time, making it a C Mo H.
Sheldon after a night of snuggling with Amy:
Sheldon: (To Howard and Leonard) "The two of you need to get your women in line!" Leonard: "...what?" Sheldon: "Last night, I was strongarmed into a night of harp music and spooning with an emotional Amy Farrah Fowler. This on a night I had reserved for solving the space time geometry in higher spin gravity... and building my LEGODeath Star. And why? Because your gal pals, Penny and Bernadette, went shopping for some wedding nonsense without Amy. An action they took with no thought or regard as to how it would affect me, the future of string theory or my LEGO fun time!" Howard: "What do you want us to do about it?" Sheldon: "You clearly weren't listening to my topic sentence... get your women in line! You make them apologize to Amy and set things right. I am a man of science, not someone's snuggle bunny!" Leonard: "Why do I have to talk to Penny? {{She's not my girlfriend}}." Sheldon: "You invited her to lunch four years ago... everything about her is on you! You make it so!"
From the same episode, Howard's magic show. Especially the exchanges between Bernadette and the kid who's not getting any cake.
Leonard showing up Sheldon in "The Friendship Contraction" when the power goes out and Sheldon suggests using glow sticks. Leonard takes out his full-size lightsaber, and tops it with a Crocodile DundeeShout Out.
Leonard: That's not a glow stick. That's a glow stick.
From "The Rothman Disintegration":
Sheldon Cooper & Barry Kripke playing basketball against each other to decide who gets Professor Rothman's office.
Leonard, Raj and Howard while watching Sheldon and Barry play.
Leonard: You know those terrible things bullies used to do to us?
Raj: Yeah.
Leonard: I get it.
Raj voicing his envy at his coupled friends, stating that
Even if I get one [a girlfriend] someday, I'd still be the guy who got a girl after Sheldon Cooper!
Amy: Sheldon told me he had a new assistant named Alex. He didn't mention that Alex was a girl.
Penny: *utterly deadpan* Maybe he didn't notice.
Amy: You're right. I don't have to worry about Sheldon.
Penny: *cracking up* No, you do not.
This bit:
Amy: I feel like I'm in high school again.
Bernadette: I know. Doing the prom queen's homework so she'll like me.
Amy: (grinning gleefully) It's finally working!
Drunk Sheldon:
Sheldon: (knock knock knock) Wil Wheaton! (knock knock knock) Wil Wheaton! (long pause) Wait, how many was that?
Also:
Sheldon: I'll tell you (telling Wil Wheaton why he's at his house). I'm from Texas. Need I say more?
And:
Sheldon: "As a matter of idle curiosity, which of your shrubberies do you feel would benefit from a thorough vomiting? Never mind, I’ll choose."
Wil Wheaton: "Oh, Sheldon...do you really think we’re gonna fight?"
Sheldon: "My fists are not up here because I’m milking a giant invisible cow."
The fake video Sheldon makes to scare Raj and Howard when they spy on his private time.
The Reveal as to what Sheldon does in that storage room: Playing hackysack.
"...and they're all taller than me, WHY IS EVERYONE TALLER THAN ME?!?"
Bernadette trying to be romantic and sexy with Howard while horribly sick with a cold. (waking up from a 5 second Benadril nap) "Oh Howard, that was wonderful!" In addition, it was hilarious to hear the squeaky-voiced Bernadette so congested. Melissa Rauch is a gifted comedic actress and that was the first opportunity for her to really show her chops on the show.
"That was short and gross... now I know how she feels."
Amy to Bernadette before taking Penny to the emergency room:
Amy: Come on, I'll show you where the tow truck scratched my car.
Bernadette: Oh, the tow truck couldn't have scratched it.
Amy: How do you know that?
Bernadette: BECAUSE I DID THAT!
The entire satellite war between Amy and Bernadette is incredible, but the absolute peak was:
Bernadette: Gosh, Amy, I'm sensing a little hostility. Is it maybe because like Sheldon's work, your sex life is also theoretical?
Amy: Well, at least when we do make love, Sheldon won't be thinking about his mother.
The great part is Penny is trying to keep the peace by changing the subject, but after the above exchange, all she can say is a dejected "damn."
Even better. Look carefully. Penny thinks Bernadette's "theoretical sex life" line is funny.
Sheldon spanking Amy for lying to him. Little did he anticipate her enjoying it.
Penny teaching a very squeamish Howard how to gut a fish.
The absurdity of GIANT JENGA.
Stuart trying to help the girls in the comic book store and telling the other (male) customers in the store to stop staring ("It's nothing we haven't seen in movies and drawings!"):
Stuart: Well, there's manga, comic books, graphic novels - I swear I will turn a hose on you!
He whirls around to snap at the guys and then turns back to the girls with a polite smile on his face, then reacts with horror when Amy asks which superhero is "best" - "You can't say that sort of thing in here! Do you wanna start a rumble?!"
Sheldon reprograms the GPS with his voice (and adds his usual little idiosyncrasies and factoids in as well). Howard's response? "Oh, look, Leonard, there's a bridge... Drive off it."
Penny and the mimosas.
The entire subplot with the girls in "The Bakersfield Expedition". While the boys are away they read a couple comics to see what's so interesting about them, and come to the conclusion they're stupid. They then get into an argument about the exact meaning of only Thor being able to lift his hammer, and in their search for answers read the comics again then dig head into Leonard's apartment to start reading the comics there, all the while arguing semantics over what qualifies as "lifting" the hammer and how it's decided one is worthy of doing so. The arguments being tossed perfectly mirror the frequent jousting the boys got into in earlier seasons, and when they come home and hear what's going on, they're stunned by it.
More from the above episode, after getting their car stolen the guys are walking across the desert road hot and miserable. Sheldon (dressed as Data) goes to give a Rousing Speech comparing their plight to the Star Trek crew exploring an unknown planet. Just when it seems like he's about to inspire them to move on a car drives by and a guy throws his smoothie out at him staining him and his outfit. His response? "I hate this planet!"
Penny absolutely spazzing out when Sheldon admitted that he may consider a physical relationship with Amy at some point in the future.
Everything with Raj and Howard's mother in "The Spoiler Alert Segmentation." A few highlights:
Howard: Dude, you have to leave now or you never will.
Raj: Man, you're being paranoid.
Howard: Oh yeah? Where are your clothes and shoes?
Raj: There over there on the...(see his clothes are gone) chair.
Later on...
Howard's mother: Rajesh, I drew you a bath.
Raj: (to Howard on phone) She's not going to bathe me herself, is she?
Howard: Gee, buddy, I really wish I could tell you no.
After Howard and Raj finish talking...
Bernadette: Should we go back and try to help him?
Howard: Too late now. We'll see him at his bar mitzvah.
Raj and Lucy's texting date at the library, a safe place they can talk and interact. It's a clever way for Raj to get around his mutism, but it manages some hysterical bits with the idea, including the autocorrect mistake that Lucy designs Porn websites vs. PROM websites.
Raj: (via text) It would help you to remember that I have an adorable accent.
Raj asks Howard and Bernadette to take care of his dog while he's away. Cue standard sitcom plot of missing dog. Someone else finds the dog, Raj recovers it, and then takes Howard to task over the incident. Then Bernadette fires back at Raj, berating him for knowing that he had the dog "for hours" and didn't tell them. "Now go and think about what you did!", to which Howard replies, "I think you'd make an excellent mother!"
When Howard and Bernadette are looking for the dog, they try calling for her in an Indian accent. Leading to this exchange:
Howard: Remember that for tonight. It's kind of a turn-on.
Sheldon: (keeping Leonard up) Nice to meet you, Professor Proton. Nice to meet you, Professor Proton.
(Leonard leaves his room)
Sheldon: Nice to meet you, Professor Proton. Nice to—(a slap is heard)—ow!
Also:
Arthur: (about Penny) Is she really your girlfriend?
Leonard: Yeah.
Arthur: You're the genius.
Sheldon's childlike enthusiasm for Howard's celebrity impressions.
Raj finally being able to talk to women in the Season Finale. The girls, however, quickly wish he'd go back to being silent around them.
Amy: Does he ever shut up?
And he continues talking even over the credits while you see Amy chug her wine while he does so.
Penny learns that Leonard is going to be working on a boat for a cutting-edge project headed by Stephen Hawking. Her first thought was to exclaim "Aren't they afraid he's going to roll off!" In a later scene talking with Sheldon she made a point to add "Who, as I learned, will not ACTUALLY be on the boat."
Other
It's not technically on the show, but there's Sheldon hacking into Super Bowl XLIII (The one in 2009 for non-NFL fans).
Sheldon: Go, whatever team you support, and may the other team play less effectively!
Followed by the announcer:
Announcer: Leave it to Sheldon. He hacked his way into the Super Bowl.
At Comic-Con 2011, an audience member asked who had the best "Howard's Mom" impersonation. Simon Helberg (Howard) barely got out a screechy "Howard" before admitting that's all he had. Melissa Rauch (Bernadette) took a moment to think, then did a flawless Howard's Mom voice with "What's this 'Comic-Con' you're at? Is that some sort of sex convention I saw on 20/20?"
In fact, Howard's mother in general. Gems include her explaining her inability to answer the door with the delightful information she's conducting a bowel cleanse and is "like an upside down volcano" ("Holy moly, how much liquid can be in one tuchus?!") and when Howard tells her he has some news... "I hope it's good news because I've got nothing but disappointment in here!"
