The whole thing about how Mukuro can take over people's bodies or create illusions to make them hallucinate (combined with how he constantly tells Tsuna he "wants his body"). Not to mention how his real body is in bondage gear, and is kept in a liquid-filled tank.
Mukuro's voice actor...Hot damn Toshinobu Iida has such a sensual voice...
Mukuro's pineapple hairstyle. With the rest of his long hair in a ponytail down his back.
His Bishonen looks as well, Manipulative Bastard status and thigh high boots.
Then there's how Tsuna burns off all of his clothes (except boxers) when he gets shot with the Dying Will bullet. Or how he eventually finds himself being handcuffed naked to a bed, completely under the mercy of his opponentSpanner (who seems to act like a huge pedophile around him). Overall, the two spent a long, undisclosed amount of time alone together.
Not to mention how Spanner got some prisoner clothes for Tsuna to wear that were much too big for him. The sight of Tsuna in the too big for him clothes, with the heavy handcuffs around his wrists most likely appealed to those with a Shotacon fetish.
His voice? Eargasms. Every time. It doesn't help that his duet with Mukuro has romantic implications.
Thanks to Dr. Shamal he had a weakness to cherry blossoms for a time. They would render him weak if he were to so much as look at them. He's since then taken an antidote but still can't stand the sight of cherry blossoms.
Not to mention that his bum looks a little too nice when wearing the school uniform.
And the way he wears his leather DC jacket.
Don't forget that Hibari is known not to handle alcohol well. Who knows how many fetishes he'd be fueling when under the influence. (I would love to hear him say "I'll bite you to death" in a drunken slur.)
Squalo being a complete masochist, taking every beating Xanxus throws at him (including a rock).
Bel. Dear, sweet God, Bel. Batshit insane, childish in battle, a constant Slasher Smile, a Knife Nut, sports Blinding Bangs, semi-masochistic, ambiguous gender (what? He wears a tiara. It counts), clothes that are slightly too big for him, and that voice. He pushes every button this troper has, including some she didn't know she had before.
Not to mention the fact that he's a LazyGenius with an epic evil laugh. Also, that image song. Oh god, that image song.
This troper finds it kind of funny how it's gone this far without mentioning Chrome and all of her enemies. Pretty much every single one of them have Naughty Tentacles that take hold of her. Not to mention how she was tied up, with Bel being very close to her with a knife. Of course, considering the majority of the fanbase, it is understandable why this one wasn't mentioned...
Two of the Milliflore Captains' weapons and behaviour are pretty kinky as well. Iris wields a leather flail which she uses on her squad to make them bloated while Glo Xinia weilds this as well as a squid. Too bad everyone hates them.
The evil laughter of Bel and Mukuro! Bel: "Ushishishi!" Mukuro: "Ku fu fu~" Don't even try and deny the fact that those laughs gave you a total eargasm.
It's probably just This Troper but when she and her friends saw Xanxus being nommed by a dinosaur they stared at it for a long time before one of them said 'Is it just me or is that really just... sexy?' We had to agree.
This troper, being a major Yaoi Fangirl, would just like to point out that all the Bishonen and Ho Yay in this series certainly caters to her tastes.
Not to mention the Running Gag among fandom that Tsuna's "guardians" are his own personal harem that * ahem* all take turns with him.
This troper can't be the only one who is loli for Bluebell. I mean she goes around naked half the time!
Byakuran lying in an alluring pose, with an almost seductive gaze on his face, with bandages and his clothes all torn up in various places on this chapter cover is another thing entirely as well.
And then there's his bondage outfit in chapter 274, with zippers all the way up his legs. Added bonus: the cause of the abovementioned scars - that is, wings.
And then he stole a page out of Mukuro's book by grabbing Tsuna from behind and suffocating him - meaning Tsuna's all flushed, gasping, weakly fighting back, etc. while Byakuran never stops smiling and calling him Tsunayoshi-kun.
Byakuran also smiles constantly and has signature moves where he 'penetrates you'. Oh and let's not forget his image song where he asks you to 'give him your body'. Then for some there's his blatant obsession with Uni once she escapes his grasp.
Ryohei. White hair, tanned skin, extremely muscled body, tends to reveal his upper body a lot when fighting, Hot Blooded personality, sports a scar across his left eyebrow, has a bit of a Big Brother Complex towards his sister Kyoko...
His battle with Lussuria, who is very blatantly gay and is insinuated to have necrophiliac tendencies as well. In his words his favorite bodies are the "wasted, cold, unmoving" ones. Ryohei goes topless during his fight against Lussuria and this ends up inspiring Lussuria to become his hardcore fanboy. In fact, Lussuria openly ogles Ryohei's muscular physique and says his body is "pretty nice", that he's "just his type" and attempts to take him home with him and make him a part of his "collection"... after he's kicked the shit out of him that is... Also, the fight takes place under some hot lights so during the whole fight we get to see Ryohei shirtless and sweating all over.
In his adult form, Lambo wears a cow print jacket with a very low neckline.
And the official fan art is sure to appeal to someone. Especially this picture from the 2009-2010 calender with all the guys wearing colorfully designed kimonos and looking absolutely gorgeous.
Though someone mentioned the mafia suits earlier, I can't be the only one who is totally turned on by ties. So...The Choice Battle and all the flashbacks for Gamma? Pass the tissues.
This colored chapter cover is what this Troper has been forever praying for Tsuna to turn into. Notice the look on his face, and Chrome kneeling at his feet. (Unfortunately her Magic Skirt didn't make it into the picture...)
And some people who are fond of Chrome and all the I Have You Now My Pretty scenarios she gets into might enjoy how Julie Katou kidnaps her in chapter 298 telling her they have "date plans".
Not to mention that he says that she is happily sleeping in bed. Wait... his bed?
In chapter 309 Julie actually climbs on his bed which Chrome just woke up in, offers her a change of clothes, grabs her face, gets really close, and offers to help her with changing which she is quick to decline while flushing all embarrassed like. Yep.
Daemon Spade in chapter 338 on the colored cover page. Look at those Bishonen looks, look at that Rapunzel Hair!\
The entire Inheritance Arc, regarding all the Mind Control. Especially the part where Enma was just completely blanked out and Daemon Spade just kept petting him and calling him stupid. And yes, the fact that turned me on creeps me out A LOT.
And [this scene] where Gokudera gets sick after catching sight of his sister. It looks more like he's getting screwed up the ass.