Shinji: *Slams the brakes on his motorcycle and angrily turns around* I take that back!
In Episode: Final, after a ghost story-telling session at the teahouse, Grandma Sanako Kanzaki dresses up as a Nopperabou, scaring the bejeezus out of them...including Ren.
When Shinji meets Femme for the first time, she steals his wallet. But since all Shinji has is loose change, she decides to buy a drink. Once Shinji catches up with her, she says she didn't know and offers him the drink. Shinji believes it for about 5 seconds.
Episode 29 is absolutely priceless.
Earlier in the episode, Reiko was followed by a man. Shinji decides to attack the man... who is no other than Goro while knocking himself out in the process. We then see Kitaoka and Goro with make-up on their face (in Shinji's dreams, fortunately), promptly causing Shinji to scream and wake up.
Reiko has been kidnapped. Hilarity Ensues when Shinji, Ren, and Kitaoka decides to investigate:
First, they suspect a man for being the suspect. This leads to:
Pretty much everything that Shinji and Ren did to have a look at the house of the man. At first (when Shimada becomes the decoy), it was Shinji clinging on the fence. Later when Yui takes over the decoy role, Ren takes a look... by having to stand on Shinji's back. Then, both decides to cling on the fence... this time with kids watching them. Eventually, they decided to become wise and decides to take a look from a nearby staircase with binoculars.
Pretty much the entire part after Shimada gets kidnapped. The best part is when Kitaoka inadvertently punches Shinji in the head with his deck, which causes Shinji to stomp on Kitaoka's foot once they transformed.
When Shinji and Ren takes a look from the staircase, Kitaoka calls both of them telling that the man is not the suspect. He calls them while doing a handstand.
Afterwards, they suspect that a lady is the true suspect, so Shinji decides to investigate by pretending to be a salesman to get into her apartment. Once he enters... Kitaoka is already there with basically the same plan. Cue the doorbell ringing, and REN entering in exactly the same getup as Shinji. It gets even funnier when the two of them pretend to be selling random pieces they swiped from the café, and then smugly look at Kitaoka and ask what he's got... and he whips out his business card.
Episode 30. Kitaoka's former bodyguard Megumi is an absolute ditz, constantly misunderstanding everything and clumsily making life harder for everyone. The comedic potential is endless.
First off, there's her clumsiness being the cause of Shuuichi firing her, like an instance wherein she accidentally throws a plate into the air and splatters spaghetti on his face. This later ends up saving her life from a Mirror Monster when she accidentally splashes hot ramen on it.
Megumi shows why Kitaoka even considered her despite being horrible at domestics: She was a damn good bodyguard. When meeting with Gorou, he throws her high heel into the air and curbstomps five different mooks... Before the errant shoe lands on Gorou's head.
Then there's her date. When Kitaoka finds out she's dying from a terminal disease (Like him), he decides to date her. When he gets interrupted by a Mirror Monster, he does a hilarious transformation, posing with a silent henshin. And then, the clincher, Kitaoka went through all this bullshit to find out in the end that her disease was just a misunderstanding. When he finds out, he drops his cellphone in dumbfounded disbelief.
Episode 40. Ren, Kagawa, Asakura and Toujou are fighting off a horde of Zelles (from Imperer, who was hiding in the bushes nearby) that interrupted their brawl. From the side, Kitaoka notices all of them and decides to unleash his Final Vent to take them all out. He lampshades the fact that it's been a while since he's done his incredibly cool finisher... before a Zelle knocks him over the bridge and beside a very confused Ren.
Kitaoka: *Slots in Final Vent* It's been a while since I've done my incredibly cool finisher- GAH!
Ren: *Sees Kitaoka crash onto the streets, stares at him while a horde of zelles is attacking him* Kitaoka?
Kitaoka: ... Yo.
Episode 43. Sano's Humiliation Conga on his quest to find an ally. Shinji flat out assaulted him upon seeing him in the cafe. Then he goes to Kitaoka's house. Kitaoka also refuses his offer, but he decides sends him to meet another Rider. By another Rider, we mean Asakura.
Oh, and it gets worse when he met Asakura. First, he tripped down when he met Asakura after he (Asakura) beats up Tiger. Then, Sano gave Asakura a letter of introduction that Kitaoka wrote to Sano. What did the letter say? Fool. Cue a massive Oh, Crap! for Sano once Asakura shows him the "letter", and he promptly ran away realizing that Asakura's probably going to kill him if he stays there.
In the 13 Riders Special, Shinji attempts to find an ally with any other Rider. At one point he's nearly run over by Itsuro Takamizawa's limo. Next thing he knows, he's dragged into a conference room by three very tough-looking employees of Takamizawa's. When Shinji tries to protest this treatment, the same three very scary men step in. Shinji wisely decides that discretion is the better part of valor here.