Yay HAMLET!◊ Not only did it become a rallying cry for fans, there are official t-shirts with #YAYHAMLET sold at the show.
Posting pictures of old portraits done of the historical figures featured in the show, with lyrics from the show (especially ones that sound silly out of context — and sometimes even in context) typed over them.
James Madison in general, especially his completely flat delivery of "...France." in "Cabinet Battle #2."
Photoshopping other people's faces over those of the Schuyler sisters when they strike a pose during their eponymous song.
Using "Non-Stop" and all the lines about Hamilton's endless writing as some sort of motivational tool for doing schoolwork. Often with a reference to "making Alexander proud."
"Non-Stop" references are also common in regards to Lin-Manuel Miranda himself, who between starring in his own show and developing the #Ham4Ham shows and writing songs for The Force Awakens and MoanaAND maintaining an active social media presence, really does seem to write "every second he's alive."
"HERCULES MULLIGAN!", which has become the fandom's version of the "John Cena" meme.
Comparing the Schuyler Sisters to the Heathers in Heathers, mainly because their color scheme (of red, green and yellow) is extremely similar to the Heather's portrayal in Heathers: The Musical.
Jokes about Jefferson's status as Ambassador to France, referencing Charles Guiteau's delusions in the show Assassins.
"WORK!", often along with the pose that the Schuyler sisters take when they say that line.
"Love is love is love is love is love" from Lin-Manuel's acceptance speech at the Tonys.
"What Comes Next?" was applied quite a bit to Britain withdrawing from the European Union.
"Teach the World how to say goodbye" in July 2016 when most of the original Broadway cast had to leave the show, including Lin-Manuel Miranda and Philippa Soo. The fandom repeated this for a few weeks on hearing the contracts would expire.
The many, many graduates who made references to Hamilton lyrics by decorating their caps.
King George III's line "Awesome. Wow." gets repeated a lot.
Peggy Schuyler's "AND PEGGY!", said during the Schuyler sisters number when Peggy is clearly trying to avoid My Friends... and Zoidberg status, gets usually used in videos where the "AND PEGGY!" is replaced with other shows' mention of a Peggy. The PBS documentary Hamilton's America even ends with it as The Stinger.
"How does a bastard, orphan, son of a whore..." gets used to describe controversial people who ended up in high places, generally being tweaked according to the person.
"I'm a general! Wheeeeee!" got T-shirts made out of it.
The line between Hamilton and Marquis de La Fayette, "Immigrants: we get the job done!", got a lot of mileage, especially since not long after the musical's debut, immigration became a hotly debated topic again. To the point that it got an entire song named after it on The Hamilton Mixtape, which sampled the line heavily (and other parts of "Yorktown").
Making mac and cheese Jefferson's Trademark Favourite Food, much to the others' disgust. This is the result of the fandom running with the fact that he actually brought the stuff to America, and apparently ordered 70 pounds of noodles between November and December 1809 alone. People in the fandom often refer to Jefferson as "Macaroni Fucker" because of this.
Singing "You don't have the votes" at the failure of any legislation the person is against. Became an Ascended Meme when even the ACLU started using it.
References to "being in the room where it happens" are commonly applied to either politics or to seeing the show in person.
Many students are also using lyrics and imagery from Hamilton to decorate their graduation caps. It's called the Hamilgrad cap.
Hell, just SEEING Lin-Manuel Miranda or other Hamilton alums on literally ANYTHING EVER on YouTube prompts commenters to remark, "I came as soon as I heard", which is taken from the song "The Reynolds Pamphlet".