The entire flashback confession between Rusian and Nekohime. Even his teammates, minus Ako, couldn't help but laugh about his humiliation. Extra funny when you realize that Nekohime is an actual girl in Episode 3, particularly Hideki homeroom teacher.
Rusian: (annoyed) You guys don't have to laugh that hard! Schwein: (through gut-busting laughter) That chapter of your life is beyond dark! Apricot: (same reaction, with matching expression) Ah, the majesty of young love!
When Ako reveals she's actually a female player, Apricot decides to reveals his true gender as well. No one buys it, especially towards a premium player like him.
The reveal that the Alley Cats Guild consists of females while Rusian's the only male member in their guild during the first offline meetup. This definitely did not sit well for Akane when she realizes that 1) Rusian is actually Hideki, one of her classmates 2) She didn't realize that her avatar name 'Schwein' means pig in German, assuming that avatar name's an "Awesome McCool" Name.
Hideki stumbles across Ako's room, and determining her protests of 'not ready' to just be stalling, he opens her door... to discover that she's in her underwear, which is obviously just-put-on-in-a-rush. He instantly closes the door and demands to know why, even as she stammers that she just needs to get ready. But when she says it's time, he opens the door again to discover that she's now stark naked, showing that he hadn't caught her in her underwear...she was deliberately taking her clothes off.
Ako: (serious) Please be gentle.
Ako casually mentioning that she pees in water bottles when Hideki asks her how she goes to the bathroom if she stays in her room with a fridge. She says it as he's drinking some yellow-colored tea, causing an instance of I Ate WHAT?!. She then mentions she was just joking and that she uses the bathroom when she needs to.
A friend of Hideki telling him in a Flash Back where his online wife was "cheating" on him by marrying another character with one of her alternates. When he wonders why it's such a big deal, his friend then mentions making him suffer as well, and starts listing off reasons why Nekohime turned down his marriage offer. Both of them then decide they'll never marry in-game. Then in the next scene his friend does just that.
Akane telling Ako about fashion magazines being a sort of wiki guide for "Real Life Offline" on how to prepare for dealing with the outside world where they'll be doing 100% Completion whether they want to or not. She, Ako, and Hideki all suffer a brief Heroic B.S.O.D. as they think about how terrible "grinding exp" in real life is.
After staying up for three days straight (setting up payback for his hacked account), Hideki briefly assumes the doorbell is a hallucination, the first ring anyway. Once he eventually gets to the door, he discovers it's Ako, and this event occurs:
Ako:(cutely) Hehe. I just dropped by- *He closes the door on her mid-sentence* Ako:(distressed; rapidly knocking) Rusian! It's me, your doting wife! (cut to inside) Geez, what's with the harsh treatment!? Hideki:(sheepish) I'm sorry, it was just a reflex... Ako:(pouting) I expected a significantly warmer welcome. It is the first time your wife has visited your family home.
Nanako asks Ako why she considers her marriage in-game to Rusian to translate directly into real-life, she manages to make a very compelling argument by reversing the logic (a married couple in real-life refusing to get married in-game). Panicking over the fact that they've been out-logic'd by Ako of all people, the girls are reduced to begging Hideki to help resolve the situation, leaving him confused because they're trying to contact him using Kyou's character in LA.
Kyou has the guild try out some Player Versus Player action after an update is released allowing it in the game. She's immediately defeated by Akane, Hideki, and hilariously enough, Ako, who uses a "Skill seal" attack to prevent Kyou from using magic, then just bashing her down with her wand. She then wonders why despite having high attack and defense, she was so easily defeated, until Hideki points out that fighting other players requires a different playstyle and skills than fighting monsters.
When they first try out the siege combat, a random guild attacks the castle first. They are subjected to a classic case of There Is No Kill Like Overkill, as the defenders cast a lot of powerful spells and lob lots of projectiles at the attackers. Kyou's group is then subjected to the very same attack they just witnessed.
After repeated failures, Nekohime's "Elite Guard" charges, and successfully manage to take the castle for her, at least until a larger guild takes it from them. She then complains that she never asked them to do it, while Hideki and the others tease her and jokingly suggest worshipping her in the same fashion as her followers.