Ichika making all the girls Face Fault with his introduction. Capped off with Chifuyu pulling off a Dope Slap on him.
Hell, Ichika's monologues are pretty hilarious just by themselves.
Ichika's explanation as to how he beat an instructor during the exam. The dry, "I don't know what the hell happened" voice he uses is what makes it funny.
Ichika: Well, I don't know if I'd call it a "defeat"... but when the instructor charged me, I dodged, she smashed into the wall, and "Ka-boom".
Rin's look of rage upon discovering that Ichika and Houki are sharing a room.
Rin: But what does being childhood friends have to do with taking a shower?!
Ichika: Oh that. That's because Houki and I are sharing a room right now.
Later in the same episode, when Rin is trying to switch rooms with Houki, Houki snaps when Rin seems to ignore her, and prepares to strike her with her Kendo sparring blade. Ichika, upon realising this, cries "Not in the house!". It's probably a poor word choice in the translation to English, but it makes Ichika sounds like he's implying 'I really don't care if my first childhood friend attacks my second childhood friend, but if they do it in our room, they might break something!'
Houki punching Ichika in the face, and kicking him in the gut so hard it lifts him off the ground for saying he'd make good on his promise to go out with her...on a shopping date.
Has a equally hilarious and now memetic name: the Houki Pouki.note A play on the children's song "Hokey Pokey".
And Charles's observation immediately thereafter:
Charles: Sometimes it makes me think you are doing it on purpose.
The day following Laura's VT System incident:
Put the moment in context at the end of episode 8 and it's even better: start with Charlotte's (re)introduction to the class. As everyone takes in the implications ("Hey, weren't the boys in the big bath last night?"), in comes Rin through the classroom wall in her IS, firing her Impact Cannons on Ichika at point-blank range, but only for Laura to block the blow...
She then turns around, grabs and picks up Ichika while still in full IS mode, AND steals a (very long, very open-mouthed, and very hot) kiss, then followed by this statement:
Laura: I hereby declare you as my wife! It has been set in stone; I will not accept objections!
Cue dropping jaws from the rest of the class, then to Ichika who took a while digesting what just happened...
Becomes funnier in the anime, where Ichika initially sighs, as if to say 'oh great, more girl drama', only to follow it up with 'HHHHUUUUUUUUUUUUUUUUUUHHHHHH??!!!' and a look somewhere between shock and horror as his brain fully registers what Laura just said.
Ichika reciting pi just to distract himself from seeing Charlotte strip to change clothes.
And apparently Ichika's type is, I dunno, his sister, probably?
This exchange in ep 10
The Girls:You're handing him over to us?!
Chifuyu: Like I would, idiots.
May count as some sort of 'Fridge Funny', but Chifuyu tells the girls that they'll have to go all out to claim Ichika, then in Episode 13/the OVA we find she has discovered that her choice of words has led the girls to think of her as yet another rival for Ichika's affections. When you think about it, that means that at some point Chifuyu must have been thinking back to that moment, and suddenly realised "Oh ***, those girls think I desire my baby Brother!" Suddenly it's no wonder why she's at a bar when she comes to this realization.
The realization actually hit her earlier than that. At the beginning of the OVA episode, all the girls came over to Ichika's house to see him. Chifuyu happened to come home shortly after they all arrived. Ichika instantly offers to cook her a meal or barring that, get her a cup of tea. Cue immediate looks of dismay on all five girls, whose thought processes go along the lines of "OMG they behave more like husband-wife than brother-sister!" The instant Chifuyu sees the looks on their faces, she immediately decides she has to leave. Indeed, it is no wonder she made a beeline right for the bar.
Also in Episode 10, Tabane herself. Taken Up to Eleven with the dub, where she calls her sister:
When Ichika was about to kissHouki, he gets poked in the head with one of Cecilia's Attack Drones, that nearly blows his head off, followed by the rest of the harem chasing them down in pure jealously.
Special mention to Charlotte and Laura; the former for breaking out of her Nice Girl image; the latter for this:
Laura: You're not paying enough attention to being my wife!
Also worth mentioning that one of them suggested using Ichika as target practice.
Cecilia's cooking skills. So much so that everyone tried to dissuade her from making a dish in the first OVA. It didn't stop her from using one of Blue Tears' Attack Drones on a metal pot, though.
To give an indication, from what we see of her dish, it's a glowing molten sludge containing meatballs, to which she adds what appears to be tomato ketchup and tabasco sauce. And by 'adding' we mean empty the entire bottle(s) into the pot.
Made funnier by the fact that when using said attack drone caused the pot's contents to explode, her response is a completely calm "Oh drat it" which makes it clear that this is a frequent result of her 'famous IS cooking'.
Taken Up to Eleven in season 2 episode 10 as she somehow "weaponized" this to render at least 3 of the girls sick. Even to the point of making her attempt at sweet and sour pork explode.
Not quite as bad as the above example, but the fact that Laura uses a serrated combat knife to cut up potatoes is...telling.
Laura and Charlotte spend much of Season 2 episode one together, with gratuitous and hilarious levels of Les Yay, including an Indirect Kiss, and Charlotte in a butler outfit serving tea while sparkling. Also, it starts out with Laura talking to Charlotte over breakfast.
Season 2, episode 2. The amount of trolling Tatenashi threw on Ichika is just hilariously high...Then come the Disproportionate Retribution.
Chifuyu ordered Char to "demonstrate" Rapid Switch ON ICHIKA, in front of the entire class, no less.
Ichika nearly got slashed by Laura and Houki in their partial IS, but got saved because Tatenashi is around.
Among the ideas of class 1-1 for the School Festival "Orimura Ichika's Host Club", "Twister with Orimura Ichika", "Pocky with Orimura Ichika" and "King's game with Orimura Ichika". Ichika's response? A Big "NO!". Cue objections from the girls.
The Cinderella play during the school festival. Finally animated in season 2 episode 3 and just as full of lulz.
One moment in particular: Ichika is press-ganged into playing the "Prince Charming". He attempts to flee from Rin and Cecilia (who are, of course, the Cinderellas), who are attacking him with thrown kunais and a sniper rifle. While in hiding, Charlotte helps Ichika escape, but they both fall down a steep incline. He wakes up in a atrange, completely dark place, and wonders if he's dead. He reaches upwards and grabs onto something...soft. You'd think, "Well, of course Ichika's going to grab Charlotte's breasts...", but you're wrong. The "dark place" is underneath her Pimped-Out Dress and he just grabbed her ass.
Season 2 episode 5: Ichika's surprise Birthday present from the girls - all sorts of Fanservice with a Smile, much to his annoyance. And it was all Yamada-sensei's idea: (Do not read this part without watching the ep.)
First up was Houki who served him a solemn tea ceremony of sorts while donning a Miko Fox outfit, complete with twitching ears. In between she initially thought that he was staring at her ample chest, but then he reached out for the fox ears.
Cecilia came next, teaching him billiards while in a Playboy Bunny Outfit. Surely enough, Houki (who ended up watching from the sidelines) stood up in anger when Cecilia was guiding Ichika into hitting the 9-ball, with lots of teasing thrown in for good measure.
After that was Charlotte's turn (complete with shifting stage sets), who served him heart-shaped cookies in a "French Poodle" outfit. Unfortunately, when one of the cookies flung upwards and landed on her cleavage, she got red-carded for being "too lewd" when she offered him to take the cookie.
Cue Rin (who was then watching from the dressing room) punching the screen while complaining that he was being "entertained" because of the boobs.
Laura followed up with her offering of a dart game involving a large prize-vending machine... and apparently (due to budget constraints) some of Laura's belongings. Ichika actually won Laura's school swimsuit in the process.
Then, what was supposed to be Rin's presentation to Ichika ended up with Tatenashi cranking the already-borderline Fanservice Overload Up to Eleven.
Even Chifuyu is so appalled at this that she does a Face Palm.
Season 2 Episode 6. Disappearing panties = Serious Business. Doubly funny in that Laura actually wants Ichika to see her panties, so she shoves an underwear catalog in his face and demands him to "pick his favorite". Triply funny in that Laura is the only girl in the harem that wears pants as part of her school uniform, so her desire to have Ichika "accidentally" see her panties is low-to-nonexistent.
Plus, the fact that Laura gets an already fake famous historical quote completely wrong. This is even more hilarious considering that Laura is German and Charlotte is French.
Episode 7: Laura flips out when Ichika reveals he's already chosen a tag-team partner for IS training and it isn't her. She summons her IS arm and is about to hit him with it when Chifuyu suddenly hurls her across the room, berating her for unauthorized IS usage. When Laura tries to protest by saying this is a matter between husband and wife, we get this exchange:
Laura: Instructor, this is a problem between husband and wife!
Chifuyu: Husband and wife? You Fool!! I'd never accept a rude girl like you as my sister-in-law!
In Volume 8, Ichika's first person tsukkomi to the IS Academy is hilarious when he was told that he will be the one MEASURING the student's bodies.
Ichika: JUST WHAT IN THE WORLD IS THIS ACADEMY THINKIIIIIIIIING!?
His train of thought in the anime shows that it was most likely Tatenashi who set that up.
He's freaking out so much that Chifuyu hands him a piece of cloth to act as an eye wrap. Ichika is immensely grateful and ties it around his head. He then discovers the fabric is see-thru... For all her seriousness, Chifuyu does troll Ichika quite a bit herself.
During episode 10 of season 2, Cecilia has the other girls help train her in cooking. Due to her Lethal Chef skills (which includes spraying perfume on the food to make it look better!), the various girls who were helping her and later taste her food end up sick the next day. Rin is Genre Savvy enough to realize Cecilia's cooking is dangerous, so tells her to taste her own food. At first things are going well, until Rin mentions needing "fire power" (in this case, a flame appearing in the food when it gets heated enough; the stoves in the IS academy are electric and don't use fire) for Chinese cooking. Cecilia takes it literally, and summons one of her drones, and ends up blasting said food. She also laments to Ichika the next day that the food "exploded" when she was cooking it. This was also a Call Back to the first season's OVA where she tried to use her IS's drone to heat up a pot... and ended up "cooking" a burnt pot for her troubles.
Also earlier than that, Houki gave Cecilia some ginger and garlic and told her to grate them. Cecilia drops them instead. This is because there was a Pun in Japanese where the verb "to grate" sounds exactly the same as the verb "to drop" and Cecilia is very Literal-Minded. Then Houki tells Cecilia to heat up the canola oil. She does so... by hugging it tightly as if she's Solid Snake keeping rations warm in Alaska by equipping them.
Earlier than that, every girl (except Charlotte) is glaring at the newest girl to have fallen for Ichika, Kanzashi, since they all believe that she has confessed her love and then started dating him. Kanzashi, being the shy girl she is, almost crumbles under the pressure. Charlotte, being the Nice Girl she is, takes pity on her and offers her some juice, which Kanzashi gladly accepts. Charlotte then proves she's Not So Different from the other girls by abruptly demanding to know what happened between her (Kanzashi) and Ichika.