Archive Binge: Three strips a week for over 20 years. Good luck.
The comic's usual avoidance of "the dreaded continuity" (the rare actual ongoing storylines rarely last more than a week's worth of strips) means there's no need to read the entire archive in order, but the addition of a "random comic" button in the site's newest redesign means you can lose hours just by putting the backlog "on shuffle." To say nothing of the "generate comic" button, which assembles a "new" strip out of three randomly selected panels from the archive and lets the reader be the judge whether surrealist hilarity is achieved.
Part One: Confrontation, the strip for September 13, 2000, features Tycho as a turnip with absolutely zero context or explanation. The Attack Of the Bacon Robots paperback reveals that this is actually because Mike threatened to draw Jerry as a turnip as long as he put off buying a SEGA Dreamcast, but this is not explained in the strip, and this was before the News section existed, so unless you've read the books, good luck figuring out what the hell is going on.
I Think We Got Everybody. Gabe and Tycho are discussing video games they like when, out of nowhere, Tycho points out the cat and an eggplant shaped like Abraham Lincoln. Tycho merely states it's cool when Gabe asks if anybody asked for that.
Broken Base: The reaction to "The Sixth Slave" was rather... mixed. Not helping this was Gabe's response — that it was no different from their trademark style and the dickwolves were no worse than the Fruit Fucker 5000, a rapist character who'd been in the comic for years.
Pretty much any character introduced for a one-off joke can be guaranteed to become a fan favorite, leading to many an Ascended Extra. Examples include Div, the Fruit Fucker 5000, Twisp and Catsby (also Springtime for Hitler) and the Broodax Imperiate.
Tycho's niece, Anne, also known as Annarchy, won a poll by a landslide to determine which character to focus on as an arc during the authors' trip to Comic-Con 2011. Hence, Annservice.
The punchline of this strip was a lot funnier before the infamous shooting of Harambe the Gorilla when a child fell into his enclosure.
Directly addressed in the news post for Craniomeganumerophila. They had already completed the Madden themed strip the Friday before the shooting at a Madden tournament in Jacksonville, Florida.
Some episodes of the Penny Arcade: The Series web documentary showing two employees' getting engaged can be a bit sad to watch now almost ten years later with the knowledge the marriage didn't last.
On September 6, 2006, Penny Arcade released a comic mocking the then-ongoing backlash against JRPGs, with the commentary arguing that, while taste is taste, arguing that such games are bad because they aren't something else is petty and illegitimate criticism. Twenty years later, it's turned out that the JRPG backlash in general was not only overblown, with the genre undergoing a renaissance of both commercial success and popularity, but something that Japanese developers were both aware of and hurt by.
This strip, which is now accidentally brilliant because it makes perfect sense that anyone with knowledge of the future at the time it was published wouldn't remember that "Revolution" was the codename for the Wii rather than a huge historical event.
And this infamous strip, whose mockery of the bogus release date for Duke Nukem Forever was funny in 1999 when the game was a year and a half late, but only grew more so as the game grew two years, four years, eight years, nine years, only to loop back around to Hilarious in Hindsight when a demo of the game, now out of development hell, was released at PAX. And in 2010, when it actually came out, we had... this.
This strip became a lot funnier when a few years later Tycho actually did miss a portion of PAX due to the birth of his child.
Another one from 2008, this strip where Gabe says Guitar Hero is better than Rock Band purely on the basis that one has "Jessie's Girl" as DLC and the other doesn't; fast-forward to four years later, Rock Band Blitz would actually include "Jessie's Girl", exportable to RB3, in the soundtrack.
This strip has a squirrel with a cigar and a T-shirt that says "Fuck you" getting turned down for Conker's Quest, for not being "accessible" enough to kids. Eventually, Conker's Bad Fur Day came out, and the squirrel probably would have fit right in there.
This strip, which is about retro characters that do not have modern counterparts à la Sonic Generations (namely Bubsy and Ristar) is pretty funny since Bubsy did eventually get a new game in 2017. Still no future Ristar, though.note But he did appear in Sonic & All-Stars Racing: Transformed as a flag-bearer, for what it's worth.
Any number of comics like this one mocking serious racing sim games and the type of people who play them became retroactively more hilarious after Mike himself watched Ford V Ferrari and got obsessed with racing. PA now has its own league in iRacing which has been running for two years, and Mike and Jerry have streamed Motorsport Manager on Twitch.
Ionosphere has Gabe complain that the web swinging in the new Spider-Man game is unrealistic because the web swing aren't actually attached to anything, citing Central Park as an example. Six years later, a Spider-Man game came out that actually had realistic web swinging, and going through Central Park is indeed a hassle.
The 2014 Valentines' pins are heavy on the yay, what with the motif being Gabe and Tycho happily sitting together on a park(?) bench, the perspective making it seem as if their hands are touching, with a huge heart in the background.
Gabe first suggests there should be an episode of Star Trek: Strange New Worlds where aliens steal Captain Pike's shirt so he just has to go around the ship shirtless, and Tycho dispenses with all subtlety by saying he can see an episode where there's a time thing leading the Enterprise to come to our Earth and Pike has to have sex with him a bunch of times "to, like, help the ship". Gabe declares that they should be writing Star Trek after hearing that.
Thanks to Paul Christoforo's very public name and shame on the website, his face (taken from his Twitter account) quickly got associated with terrible customer service. His horrible emails - both in terms of content and grammar - supplied such memetic gems as 'Son Im 38 I wwebsite as on the internet when you were a sperm in your daddys balls and before it was the internet'.
In the more traditional sense of a meme, the word "bullshot".
In the early 2000's internet, cardboard tubes were often jokingly treated as "ultimate weapons" in reference to the Cardboard Tube Samurai.
They Changed It, Now It Sucks!: In early 2003, the comic underwent a shift in art style to a somewhat sketchier look. This caused some initial backdraft, if mainly out of the suddenness of the change than anything else. These days, style changes to match the tone are considered the norm.
Values Dissonance: Considering it's been going since the 90s, it's inevitable some things wouldn't age well. Some early strips could have some rather strong language, using words that would eventually go on to be see as slurs in the modern age. (Notably, the word 'retard' could be thrown around by the characters a few times in a derogatory context.)
strip.Tycho: What's topping? Let's top. I want to top.