Making the group into the most popular people in school after taking control of the supply of chicken fingers.
After Jeff turns his meta gimmick around by saying it's "so season one," Abed retorts that he does know the difference between reality and TV: TV makes sense and has likable leading men, while he's stuck with Jeff.
Befriending a pregnant classmate, beating up her deadbeat boyfriend, and helping her give birth, all in a literal Out of Focus subplot.
Doubly awesome as he'd stated in the previous season that he'd NEVER MADE IT PAST THE SHOW'S OPENING CREDITS.
Being the only one in the group to pass a sanity test (though Jeff had admitted to filling his out randomly).
Bat!Abed's interrogation of his landlord in "Foosball and Nocturnal Vigilantism" somehow manages to be awesomely Batman-esque despite the fact that Bat!Abed struggles to get into the apartment through the window in the first place and then struggles to make it across the room after getting his cape caught on the window ledge.
Conning Jeff into revealing more about his father in Paranormal Parentage.
Geothermal Escapism is good day for Britta, between immediately identifying Abed's game of The Floor is Lava as an attempt to avoid facing Troy leaving, outdueling Jeff, and finding a way to help Abed face reality.
Beating the Phys Ed teacher at pool, completely naked.
And earning each other's respect.
"Banged Mark's mom. Twice."
His super-intimidating threat to beat up Pierce if the promise of his father's arrival is a lie in any way.
... and there will be nothing madcap or wacky about it.
Figuring out the whole yam sabotage plot, including refusing to let Todd take the fall despite everyone hating him.
Him plowing his way through the Hunger Deans, especially his tango with the Dean where he even pieces together the Dean's plan to prevent him from graduating.
Season 5 gives us Jeff beating the ever-loving crap out of Alan to the point that the latter is on the ground whimpering like a child. This is preceded by a chilling half-monologue about Poking the Dragon which he decides to cut short because Alan isn't worth one, showing us just how much of a badass he can be.
His acid trip
Having the where-with-all to make sure everyone in the group passed Spanish, by sleeping with the teacher.
His stint as a Magnificent Bastard in Dungeons & Dragons, enslaving the Big Bad dragon of the story and ambushing everyone else, then freezing them all.
His eulogy for his father, declaring that he's no longer afraid of him, he wins by still being alive, and his dad can suck it.
He gets to stick it to his father some more while playing a video game for his inheritance, riding a nuclear bomb into his father's One-Winged Angel form. "LOOK AT ME NOW, DAD!"
"KICK... HIS... ASS!"
"It's December 10th!"
Going absolutely medieval on Abed's camera equipment with a baseball bat.
Showing a skeptical Jeff how great a foosball player she is.
Pretty much anything foosball-related she does in that episode is awesome. "KILL OR BE KILLED!"
While playing Cornelius' video game, Annie accidently kills a blacksmith. Upon being told that real world morality doesn't apply to video games, Shirley kills the witness to the murder, the blacksmith's wife, steals anything that isn't bolted down, and burns the hut down. In a game she had been playing an hour, two hours tops. Beware the Nice Onesindeed.
And don't forget when she becomes head of the campus.
Troy deciding to man up, by stripping down to a leotard and helping Britta on stage.
The entire last act of "Epidemiology," where he escapes the library, but goes right back inside to save everyone from brain damage, even pushing through his own impending zombiehood after he's bitten, complete with a bunch of Bond One Liners. A very good showing considering his falling victim to Black Dude Dies First in "Modern Warfare."
Abed: Make me proud, Troy. Be the first black man to make it to the end.
"We're learning to teleport, and we're helping our friend find the meaning of Christmas!"
"No, no. Take him to the police. He murdered someone. Take him to jail... You guys are weird."
Really, the whole season 3 finale is a crowning moment of awesome for Troy. First, he not only figured out how the Vice Dean of the AC repair school was murdered, but he then challenged the murderer to an air conditioning duel where the opponents were locked into the Sun Chamber. In separate chambers the two had to fix their own air conditioners while the temperature continued to gradually rise. During the duel, Troy acted completely calm even while the murderer was frantically trying to fix his own air conditioner. Troy then fixed his in less than thirty seconds and sat back while his opponent was slowly overcome by the heat. Finally, Troy fully embraced his role as the Truest Repairman and now seems to control the entire AC repair school which is incredible considering how much influence the AC repair school seems to hold (at least over Greendale).
Troy saving Abed from a psychotic Inspector Spacetime fan.
Troy: Have you ever been in a fight? *makes a fist* Because I have.
The fakeout about his death when the gang started Spanish 102.
I am a man who can never die.
Salvaging Annie's anti-drugs show after Pierce gives it a pro-drugs message, turning his antics around to a genuinely effective way to get through to the kids.
From the Season 2 Premiere Betty White's character June Bauer shooting Starburns with a blowdart and then later the weapon she chooses to attack Jeff with while he defends himself with respect.
To clarify, when Jeff picks respect instead of the 7 tools for the assignmet as what's most important in a group (and gives a heartwarming speech) she reveals they all combine to make an awesome weapon that she uses to choke him with:
Jeff: I respect you. Professor Bauer: And that is why you fail.
Professor Duncan, upon realizing his restraining order against Chang serves as a kind of force-field, proceeds to make Chang's life hell.
From the pilot, his prank making Jeff think he would be getting a free ride at Greendale, only to give him a "cheat sheet" that's empty except for "Boo yah."
George Takei narrating "Epidemiology," and giving anyone named Kevin a free voicemail message.
In "Conspiracy Theories and Interior Design," Professor Garrity coming out on top of the Gambit Pileup the third act devolves into, with the help of his cop friend.
Starburns getting the entire class to walk out on the Spanish final back in season 1.
Gilbert from "Digital Estate Planning" has one every time he shows up, first as a Magnificent Bastard villain who would have won halfway through the episode if Britta hadn't accidentally made a poison instead of a strength potion, and then being the one to take his horrible father down after his Heel-Face Turn.
Another one that doubles as a Tearjerker: "Decline."
The riot from "Course Listing Unavailable".
Abed's introduction, jumping over Jeff, running on the wall, and plugging Leonard, following it up with the appropriate Terminator reference.
Annie ambushing the guys from a bathroom trash can.
Additionally, the following music right after "Somewhere," taking Greene Daye's next Irish jig and breaking it down into a triumphant dance number for the group.
Also "I am senor CHANG!"
Also, "College is a Party!"
Four words: "Donde... esta... la biblioteca..."
Four more words: "Kingdom: Animalia... Phylum: Chordata"
"All my boys and all my peeps like to wear nightcaps when they go to sleep!" The full version on the soundtrack is awesome, catchy, and hilarious, with lyrics like "I'm gonna sleep like an old timey dude tonight!"
It's called 'Episode 119 Medley,' and is included on the season one soundtrack.
Gravity and its awesome tip of the hat to fanvids.
The genius that is "Getting Ridda Britta" and "Pierce You're a B."
And Pierce's rebuttal in The Tag. After seeing Vaughn acting like a petulant child & writing songs insulting Britta & Pierce, it's very satisfying to see his reaction to the rap Pierce wrote to insult him.