Disabling adult content can lead to a complete mood whiplash because of the way that sex scenes are censored. Once the sex starts, the game flashes to a random, unrelated image, and then cuts to after the sex ends. Since the choice of image is completely random, some players have gotten an image of fried shrimp in Hanako's route, after she shows Hisao her severely burned body. The unfortunate coincidence is simply hilarious.
This video, parodying the "I love you Rin Tezuka" and "I love you Emi Ibarazaki" videos.
The April Fool's Day blog post's discussion of subscriber features, particularly getting the option to tell Kenji he's cute or propose a threesome with Shizune and Misha if you pay for it.
Also in April Fool's, the amusingly stilted deliveries of the voice acting samples, including Misha's trademark "WAHAHA~!" laugh. With Shizune you get thirteen seconds of silence.
The promised "HD" version of Katawa Shoujo that is said to have been stripped of anything remotely offensive i.e., anything other than the title screen.
Hisao trying to get out of listening to Kenji's first rant about the "vast feminist conspiracy".
Hisao: Stop it. Stop! I lost you way, way back there somewhere. Somewhere around "feminist infiltration". Kenji: Too hard to follow? It's cool, I have some graphs and stuff in my room. And puppets. You like puppets? Hisao: No puppets. Kenji: You don't like puppets, okay. Graphs are still cool though, right?
Kenji bursting in on Hisao butt naked while Hisao is in the shower, to ask for money. And to rant a bit about feminists again.
Hisao: Must be a pretty crappy movement if it all hinges on one naked guy, ranting in a bathroom at another naked guy.
Hisao's reaction to one of Kenji's first inane rants:
"I have never seen anyone talk so heatedly and so defensively about absolutely nothing before."
For that matter, Kenji's inane rants, period. They really have to be read to believed.
Kenji: "That blind broad is up to no good. I can feel it in my spleen, man. Her presence is like a dark shadow that's in the way of my great vision! As expected of blind people."
Kenji: But, basically, when I hear a phone, I get nervous. It's my darkest secret. I have two theories on it: either I have some fear of receiving some undefined, ominous, life-altering doom call, or I was beaten with a phone in the past. Beaten so badly I can't remember it.
Hisao: Beaten in the head.
Kenji: Well, where else could I get beaten with a phone that would make me unable to remember it? The ass?
Hisao: I thought you didn't go outside.
Kenji: I wear a hat now.
I decide not to point out that he is not wearing a hat.
In Rin's route, when he mistakes Rin for a male and extends an invitation to join his anti-feminist movement. Rin doesn't even realize what he's talking about because of his vague phrasing and her Cloudcuckoolander nature.
During Lilly's route, he finds Hisao in the cafeteria and they decide to have lunch together. While looking for somewhere to sit:
Hisao: Seems like it'd be hard to find an empty table.
At one point in Lilly's route, Kenji accosts Hisao to rant about how Lilly is in the mafia, which leads to this exchange:
Kenji: Now answer me this: who has lots of social power, is filthy stinking rich - you know all blondes are rich, right? - has a long history of disputes and used to belong to a much larger organization?
Hisao: The Roman Catholic Church?
Kenji: ...Well okay, there's that.
Even more hilarious is that Lilly actually attended a Catholic school before coming to Yamaku Academy.
Rin taking just a little too much cold medicine. And the subsequent reaction the following day with a hilarious wall of text.
Rin deciding that Lilly has stolen her and Emi's usual lunch spot on the roof, and declaring that a nearby yellow butterfly is Lilly's accomplice and was scouting the area for her. She concludes that Lilly is a "butterfly whisperer".
Rin casually walking in on Emi and Hisao after they (kinda) have sex for the first time, saying she needs to use Emi's window to look for a cloud that had passed her own window, then walking out without even seeming to notice that Emi is clad only in panties. Mind you, she probably DIDN'T notice. After all, she doesn't consider it to be inappropriate to answer her own door clad only in panties and an unbuttoned shirt.
Emi: Yeah, my morning run really works up my appetite. Which is great, because then I burn through lunch pretty quickly! Helps me keep my girlish figure.
Rin: What would happen if you lose it? Would you become a man?
Emi: It's a figure of speech!
There's quite a lot of funny moments in Emi's route: saying that the "runner's high" is Better Than Sex, Shizune's incredibly wordy (well, as wordy as someone can be with Sign Language) and pompous rant on public displays of affection, Hisao's equally wordy and pompous response...
To sum up - at one point, Hisao states that her facial expression is "almost comical". This is an understatement.
It's even more hilarious for some people because it's quite clear that neither Hisao nor Emi have any idea what they're doing.
A minor one, but on Lilly's route, Hisao getting Emi into a deal where they both agree to share their English test results on the count of three, and then doing what anyone would do in that situation. Emi's reaction is wonderful:
Emi: Alright, on the count of three. One...Two...Three! Thirty Two!
Hisao: *silent grin*
Emi: Ah! Evil! Evil, evil, evil, evil!
Hisao hears that Rin caught Emi's cold, and worries that he might be at risk too:
Hisao: It would make sense, after all. Emi and I were in close contact the other day...
Hisao's visit to the Shanghai with Rin and Emi in the former's route gets a particularly hilarious twist if you've played Emi's route first. More specifically, her choice of pie gets a particularly hilarious twist.
After Emi gets a leg infection and is wheelchair-bound, Hisao comes to her room. While helping her into bed:
Hisao (Thinking): She's actually a little heavier than she looks. It would be rude of me to observe this aloud, of course.
Hisao: Man, you're kind of heavy.
When Shizune and Misha corner Hisao on the third day he mentions that the only escape would be to jump out of the window. To any Genre Savvy players who are hoping for a Crazy Awesome option he says the following:
Hisao and Shizune throw Rock-Paper-Scissors over which one of them should have a veal cutlet bread. They tie. Seventeen times.
The great part about this is the final time, in which Shizune declares that she has figured out Hisao's mindset and will definitely win next time. They tie again, resulting in Shizune getting a Flat "What." expression on her face and Misha (and the player) doubled over laughing.
Occasionally, but rarely, Shizune gets an evil cat eyes expression (>:3). When it does pop up, you'll be busting into laughter.
This one◊ appears only once, and it's just as funny if not more! (°^°)
Shizune's over-the-top rant on the new council at the end of her route. "They're like a heavily-marketed but mediocre, big budget, critically panned sequel to the acclaimed, low budget Sleeper Hit".
At one point, Misha bursts in to Mutou's room, saying that they need more plywood to build stalls for the festival. Then this happens:
Looking at the two of them communicate is terrible, like looking at a man being tortured by drilling his skull open while blasting pop music at full volume at the same time.
Hanako having a bit too much to drink at her birthday party. Her normally cautious and concerned facial expressions are replaced by a big dumb open-mouthed smile, and a silly looking pout. It's somewhat amusing to see her act so out of character.
Hanako suddenly hiccups and accidentally knocks over the doll.
Hanako: I...think I should maybe go to bed. T-thank you, Hisao, thanks Lilly and Aaaaakiraaaaa.
She slurs Akira's name pretty hard, barely avoiding breaking out into a giggle midway through. She's completely plastered, and I can't decide whether I should feel a little bad or not for being amused at the state she's in.
There's also Hanako's dopey smile once the alcohol hits her.
"Hang on a sec, Emi, just let us get our pants back on."
Don't worry, there is nothing of that nature going on between the Nurse and Emi. He's just a gadfly and does it for the afraid/disgusted/something-else-entirely reactions Hisao has. In fact, they have a game where he tries to get get Emi as flustered as possible.
The nurse joking around with Emi and Hisao in his office. He tries to get Hisao to lift up his shirt to check his heart ("Sorry Emi, I tried to get you a free show.") Then this conversation happens:
Nurse: "If we don't get you on your way soon, Emi will think we're up to something." (*wink*) ...
Emi: "What took you so long? Now I'm going to be late!"
Nurse: "I was just seducing Hisao, that's all." (Hisao tries not to blush.)
Emi: "What!? Come on, what have I told you about seducing my friends?"
Nurse: "I'll try not to do it again, though I fear young Hisao may be lost to the female gender forever."
He's worried about Emi so he calls her mother: "Meiko, your daughter's being a pain in the ass again."
Hisao does a Spit Take after Kenji describes a dictionary as "the medium our ancestors used to look at porn," ruining a book. As he fears having a heart attack over paying 7900 Yen to replace the book, he tells Yuuko "I'm trying out grape cologne!". She not only believes him, but continues to do so in a later scene.
Lilly's sister Akira can be hilariously frank at times, such as just after learning that Hisao and Lilly are dating:
Akira: "Atta girl." *leaves Hisao still looking flustered*
Though even Akira can be serious at times. Like when she and Lilly take Hisao and Hanako to a jazz club on Hanako's route. Lilly, Hisao, and Hanako are all underage, and not technically allowed to be at the bar in the back.