In General

Kintaro's weird toilet fetish, which usually ends up with him being caught by the person he's fantasizing about. In Episode 6, it ends in Amusing Injuries.
Kintaro's reaction faces, all of which are hilarious, but with special notice given to this, this◊, and this one◊.

Episode 1

Kintaro walking menacingly towards some Yakuza harassing an old couple that had helped him earlier...then abruptly walking into an alley away from them.
Kintaro losing control of himself after misinterpreting C-Base as something beyond first, second, or third base.
Kintaro: YES! YES! I LOVE PROGRAMMING! C-BASE! C-BASE! I WANT TO GET TO C-BASE!
Madame President: YOU'RE FIRED!
Kintaro: Ehh?
The "black bra" scene.
Kintaro getting knocked out in slow motion.
When Madame President destroys Kintaro's notes.
Kintaro: ...Those were my notes...those notes were more valuable than my life! Money can't replace that kind of knowledge! THOSE NOTES WERE PRICELESS! (realizes he's showing her the notes he made of her, including his erotic doodles) ...AWW, SHIT...
- The delivery of the "AWW SHIT..." in the English dub makes the entire series worth the cost of the DVDs alone.
After Kintaro admits he already spent the money Madame President gave him for the accident earlier in the episode, she freaks assuming he blew it all on booze and hookers (he actually gave it to the old couple who were being harassed) and contemptuously spits at him. Kinatro catches it in his mouth. She goes fucking ballistic on him.
Madame President (while kicking the ever loving shit out of Kintaro): DIE DIE DIE DIE DIE!!!!!

Naoko has a change of heart after setting up Kintaro for sexual assault, but not before he has been pummelled almost beyond recognition by her father's henchmen. His response:
Kintaro: I just wish...you had been sorry...a little quicker...*(passes out)*
Kintaro's Homer-like screams.
It may be vulgar, but it's hilarious when Kintaro's hand takes the shape of a penis.
Kintaro: If only my hand was my penis~!
Naoko's internal monologue as she teases Kintaro.
Aww, look at that boner! Boioioioioing!
He's so silly with that perverted look on his face. And, the way his thwobbing ewection is stwaining against his pants!
What a typical man, always thinking about sex.
"OH MY GOD, SHE'S NOT WEARING A BRA!"
"WOAH NIPPLES AHOY!”
The incredibly shrill and loud maid, voiced by Spike Spencer of all people.
Kintaro's long winded rant about helping the maid as she tries telling him she's not destitute and her son's not dying, culminating in him mentioning they'll eventually form a long lasting bond of trust which the maid admits actually sounds nice.

Kogure's unintentional make-out session with Kintaro.
Kintaro: White out...
- Kintaro zipping and buttoning Noriko back up after Kogure tries to undress her.
Kintaro calling Kogure an "evil weenie".
" DATE?!?!?! "
Kogure's description of how he seduced Noriko (actually Kintaro) the previous day.
Kogure: The other day I got that little slut so hot she was moaning like a bitch in heat!
Kintaro: Really...
Kogure: That is one seriously perverted bitch.

Kintaro's huge boner when challenging the swim teacher.
"Sock it to me!"
Kintaro waking up outside with his underwear on his head. It's hard to tell if they're a pair of white briefs or if those are the panties that Naoko gave him two episodes ago.
"So! How do you like my swimming?"

Kintaro, when he finds out that Reiko is the hot biker chick from the beginning of the episode.
Reiko: You've got an erection.
Kintaro: Yeah...
- Also his Big "YES!" when she says that if he wants her, all he needs to do is catch her in a race.
"What's he think this is, a cartoon? He's CRAZY!"
The Depth Deception used when Kintaro jumps the bridge with his bike, making it look like he'll make it...then he falls about a hundred feet short of the other side.
The fact that Kintaro keeps biking even after he's won the race and the right to get laid...not because he doesn't want to stop, but because he can't.

This exchange:
Egawa: But you better make this film gripping! I want to grab the audience by the balls!
Director: I'll grab them and squeeze so hard they won't be able sit down for a year!
Kintaro: EXCUUUUSE ME!! COULD I HAVE YOUR AUTOGRAAAAAAPH?!
Kintaro indulging in his usual toilet fetish with someone walking on him, causing him to whirl around and slice some hair off the person's head with a knife he's holding...except this time, it's the manager of the studio and not the girl he's fantasizing about. He's next seen with multiple cuts and bruises that Chie is patching up.
"Wow, Kintaro, you really know your boobs!"