During Tsukune's training in Part 2, he is chained to Ruby to teach him to control his energy flow. Whenever he loses control, she receives an electric shock; the strength of the shock is determined by how much power he let loose. When fighting a large group of monsters, he releases so much power Ruby orgasms from the power of the shock.
Chapter 23 of Part II in general
This, specifically the Bus Driver in the last panel. Possibly the only moment in the whole series to make this troper genuinely laugh out loud.
From Season 2 episode 3 of the anime, when Tsukune is having an extremely awkward joint dinner with Kurumu and Mizore's moms:
Tsukune: Geez... this is way too intense...
Kurumu's Mom: Tsukune.
Tsukune: YES, MA'AM!?
From Season 2 episode 4 of the anime, when everybody's at a total loss for how Yukari grew up, Mizore just randomly suggests: "She probably slept for about ten thousand years. I heard it helps make kids grow."
When Inner Moka fails at cooking (her first attempt put Kokoa in the hospital) her friends all rally together to help her cook in an adorable moment... cut to the cooking room ON FIRE! Everyone in the room is either passed or seriously injured (Yukari is lying in a crater pinned to the wall). Cooking is dangerous business.
As much as the anime might be Fan Discontinuity, there's an absolutely hysterical scene in Capu2: Inner Moka has been permanently released due to Outer Moka sacrificing her rosary to protect the school, but she's having trouble fitting in with the Newspaper Club. The other girls fight over Tsukune by rubbing their bosoms against him. Inner Moka clears them out with her intimidating presence, and Tsukune thinks he's saved. Inner Moka then starts rubbing HER generous bosom, asking, "Am I doing this right?" Tsukune's expression can be summed up in three letters: WTF.
In the same episode, Inner Moka offers to do the "gazing into each other's eyes" thing with Tsukune. They give it a try.
Tsukune: Oh, Moka...
Moka:(flatly) Oh, Tsukune.
From the episode "Bathroom and a Vampire", Kokoa is on a bicycle trying to catch up to Moka who, with Tsukune and the girls, is visiting Tsukunes home. She's riding fast enough to overtake a truck, then a sports car and finally a train! As she rides past the train we get a view from inside one of the trains carriages. We see a random guy feeling the hostess' butt to which she responds "Sir that is not appropriate behavior". When Kokoa rides past, a woman exclaims "That girl's wearing strawberry panties!". Cue everyone in the carriage suddenly rushing to the left side of the carriage (viewers left anyway) and peering out the window to see the "interesting" spectacle.
The scene in Tsukune's house where Kurumu is chasing Mizore through the halls after an embarrassing incident in the bathroom, and Tsukune's mom's panicked reactions at the half-dressed teenagers racing around. Then Tsukune comes running after them trying to simultaneously dress himself and get them to stop, with Yukari tagging along behind him. In the anime, Yukari is following him because she keeps trying to tell him to put his pants on, and Kyouko walks in to find them all collapsed on the stairs — with Yukari trying to tug Tsukune's pants on for him.
"And what are you to him??" From right to left: "Friends!" (Moka), "Lover" (Kurumu), "Wife" (Mizore), "Concubine" (Yukari), "...toy" (Ruby).
Almost all of Haiji's appearances have at least one really funny moment in them. His peak is at Ishin Denshin, when he becomes something of a pervy man's saint (complete with a "God Bless You") to help Fong-Fong Yukari in his body and Tsukune sneak into the gym where all the girls are changing.
Moka sucking Tsukune's blood complete with him not particularly enjoying getting his blood drained. However, he's not particularly harmed either: after the first time, he still has enough energy to run around in a panic.
Chapter 47 of Part II, Fong Fong's tears in reaction to the others treatment of him.
Moka's face after being caught sucking Tsukune's blood here, and being found out here.
This scene had me laughing out loud for several minutes. Akuha's reaction is great, but Tohou Fuhai's little note made me just crack up.
A bonus chapter has the gang trying to contact a spirit via a cheap Ouija Board. Its messages are a littlebitunexpected. Even better, each of the girls has no problem playing along, including Inner-Moka
Chapter 36 of Part I, when Tsukune, Moka and Yukari tries to hide the fact that the school is a school for monster from Tsukunes cousin. It involves several bathtubs to the head summoned by Yukari as soon as anyone tries to say something about monsters (except Ruby who is lightly smacked by a dustpan), that is everyone until when Gin shows up and is hit by a giant morningstar before even saying two words.
Mizure receives a fan letter and reads it aloud for the others. Turns out the fan is a stalker just like her. The reactions the others show plus the music the scene is set to are priceless.
Hokutos insane laugh face. (Which looks more like some kind of mental rape face, by the way)
The Omake for Volume 11 apparently shows what was going on with Moka while Tsukune and co were training. It involves Moka getting awkward gifts from Kahlua, Akuha spending way too much money on treating Moka nice, and Tsukune wondering what Moka is going through and enduring while under his Training from Hell with Tohofuhai, followed by a panel that shows Moka with Kahlua and Akuha in a Jacuzzi.
The omake for Volume 6 features Yukari's mother who finally is given a name Fujiko (she only appeared twice in the manga and the anime proper and both times we never got her name), the whole omake is all about lampshading her being pretty plain and ordinary compared to the other mothers we seen up to that point and not really standing out especially when compared to Ageha and Tsurara.
A bit of dark humor, from chapter 64, the Outer Moka returns and hugs Tsukune, Tsukune then says that he's happy that she's back, and then Masked King appears behind them.
Tsukune: “Moka-san I'm so happy!”, “You got your rosary back!”.