Anything Twelfth does while onscreen. ANYTHING. With the exception of the part where he eye gouges Ninth, although even that can be looked at as a Black Comedy moment.
In episode 4, Kurusu goes to pick up Yukiteru at his house and expresses some annoyance in not being contacted as soon as he left Yuno's home. The following exchange occurs.
Yukiteru: Listen, Kurusu. About Yuno... Last night at her house, I—"
Yuno trying to kill Yuki's dad after she learns what he's up to and Yuki's attempts to stop her.
Yuno's reaction to Third's death:
"Is that all we get? Man, you'd think there'd be a little bit of blood. [stretches]"
In Episode 3 Yuno tells Yuki to drink something together with her. Yuki proceeds to try to drink, notices that barely any juice is going through, lifts up the straw to notice that the two straws are jammed together, he proceeds to say:
"WHAT IN THE HELL IS WRONG WITH YOU!!!"
It's implied that Yuno didn't do this to be all crazy and creepy stalker girl-ish, she was just trolling him. In fact, the whole amusement park sequence seems to just be her having a good time at his expense.
In episode 9, Akise is talking to Yuno, and replies to her saying she doesn't trust him when he says he wants to help Yuki by saying he's not in this to be an altruist. He follows it up with "Heh. Your man's a hottie." Both Todd Haberkorn's delivery and the sheer look of shock on Yuno's face are priceless.
Chapter 34. Yuki is trying to confess to a girl named Moe Wakaba in a flashback. Yuno runs interference. In a bunny suit. Repeatedly.
This happens in Episode 18 of the anime and it's even funnier, especially Yuno unknowingly scaring a little kid by growling.
And then this dub line happened after she interrupts his attempt to buy Moe soda.
Yuki: WHY AM I BEING HARASSED BY A FURRY?!
Episode 1 features an omake in which Mur Mur attempts to hand Third his Future Diary, with hilarious results. He mistakes her for a witness and tries to kill her, but accidentally slices trough the Diary, killing himself. After he is brought back, Mur Mur explains how his diary works. He decides to destroy the cellphone to get rid of evidence and dies again. The omake ends with Mur Mur watching a viewscreen showing Yuki killing Third. She notes that "Hasty people are troublesome".
In another Mur Mur segment, she sells Twelfth's diary to him for 50 yen, then goes to the store to buy a candy bar (as a reward for being such a good person). It costs 60 yen.
She disguises herself as Yuno to learn the secret of Ms. Amano's miso soup. First, Ms. Amano believes that Mur Mur is Yuno even though she barely comes up to her knee. Then she tastes Mur Mur's attempt at the soup; cut to an ambulance pulling away from the house. Yuki meets the same fate just a few minutes later.
Chapter 17, when Akise randomly grabs Yukiteru's ass in front of Yuno.
Episode 6: Yuki's Humiliation Conga throughout the episode thanks to Yuno and his mother. The scene in particular with Yuki trying to hold his closet doors shut while Yuno's trying to force them open so she can meet Yuki's mother.
Yuki gets so desperate in forcing his mother out of his room that he ends up hugging her and tossing her out of his room with a sumo wrestling throw, complete with calling a Ring Out once she's out of his room.
Also, in Episode 6 Yuno asks Yuki while sleeping over "You gonna put the moves on me, or not?" Yuki's reaction is hilarious.
Yuki's thoughts on Yuno while sleeping: "First time I have a girl stay tonight, and it's got to be a nutcase."
Yuki's reaction to Yuno entering the bathroom and offering him a toilet roll when he notices it's empty.
Yuno:[offering Yuki the toilet roll] Here you go... sorry. Yuki:GET OOUUUUTTTTTT!!!
Episode 8, when Yuki accidentally pulls down Hinata's trousers, exposing her underwear, there's a loooong pause then Mao takes a picture.
Episode 10 opens with Minene having a Flashback to when she tried to take on the Third. After being injured in a fall, she is found by Nishijima. Suddenly, Mur Mur begins dubbing over their (and Third's) dialogue to make it sound like a stereotypicalShoujo Manga, in which the three are in a love triangle and Minene is a Damsel in Distress.
In Episode 15, Kosaka freaks out when his apprentice diary is broken thinking he's going to die.
Mao's apprentice diary revolves around...Hinata's boobs. Hooray for boobies indeed.
Also in Episode 15 when Akise says that Kosaka has a large house that's be a good hide out, Kosaka says "All due respect man, but tough titties..." but is cut off by a smiling Mao clobbering him from behind.
In Episode 4, Twelfth does a hilarious henshin pose.
Minene on the toilet calling Nishijima a pervert, trying to flush and failing and kicking the toilet which causes it to squirt back water at her.
Wait, before that! When nature calls her first! From the camera angle when she bends down, it looks like Nishijima's bratty "daughter" needs to go while he's taking her somewhere!
Nishijima says he loves Minene and Minene retorts that he just wants to have sex with her to which Nishijima responds "Pretty much".
Minene is pretty funny with her facial responses to certain things like when Nishijima tried to put a ring on her finger.
Akise and Mur Mur's antics in the spin-off Paradox, where they face Minene. Akise straps a bomb to Mur Mur and sends her flying towards Minene on rollerskates to disable her. It turns out the bomb is a fake.
Minene's idea of what a marriage is and the accompanying images that go along with it. The dub is arguably even funnier, as she sounds more and more sick of the thought with each line.
Minene: Shut the hell up. I'm being proposed to?! [cue the dream sequence, starting with them at the altar] Oh god. [they cut the cake] Ohhh god... [and then the baby pops out of the cake] Ohhh god!
Twelfth arresting Third in the last episode of the anime, and later visiting him in prison.
Episode 5 has Tsubaki having her face introduced to the wall thanks to Yuno. Her response?
"If I didn't know better, I'd swear you did that deliberately!"
Episode 11 has Yukki taken hostage by Ninth, a destroyed floor separates them from Yuno; and then Yuki accidentally blows up the floor behind him and Ninth, causing them to both get stranded.
The conversation between Minene and Nishijima about Yuno's dead step-parents is a fairly serious conversation. The mood is lightened by the fact that Minene has a chipmunk eating a piece of cheese in her shirt.
For all the awesomeness of his Big Damn Heroes moment in saving Yuno, actually seeing Yukiteru swinging an ax in Episode 5 (at least when taken out of context) is actually pretty damn funny, at least when compared to Yuno's skill with the self-same weapon.
In the Redial OVA the girls threaten to (non-seriously) drown Kosaka in the ocean after he insults them. We then cut to Mao and Hinata burying him in the sand.
Before that, Mao accidentally groping Hinata and perving about it. And then Yuno deliberately gropes Hinata.
The wedding rehearsal, where a short, old lady begins fitting Yuno for her dress and spends the entire time ranting and berating them about "kids these days" and how people their age shouldn't be getting married.
Episode 3's omake has Mur Mur taking Yuki's advice in trying to be popular with kindness, (his example being making someone a late night snack just because). Cue Deus finding and looking at a small snack tray on his throne's armrest.
Yukki's mother giving her son the go-ahead to do whatever he wants with Yuno:
"Night-night! And have fun storming the castle! (Beat) And remember to keep that little rascal wrapped until you're married!" (has pillow thrown at her head and leaves)
Episode 14's Omake features Kosaka at a hot spring. He finds Mur Mur lying face first in the water and freaks out thinking she's a corpse.
Kosaka: Holy shit, there's a dead midget in the pool!
Yuki's line in episode 25. Also a CMOH.
Yuno: Dammit, Yuki, why do you always have to interfere?!
Yuki: BECAUSE I LOVE YOU, YOU CRAZY BITCH!
Gets even funnier when you consider that in the Japanese version, Yuki simply says "Because I love you." One could almost see English dub actors holding their sides while trying to record the rest of the episode.
From the camera angle when she bends down, it looks like Nishijima's bratty "daughter" needs to go while he's taking her somewhere!