Relationships in cartoons can be beautiful and idealistic things. Proof is found in the near-limitless fan fiction and fan art depicting the consummation of beloved animated romances. These R-Rated works are developed because cartoon developers and artists have always stopped just short of showing the more physical aspects of relationships in the mainstream. Whenever references to sex and attraction are made, they're usually in the form of tongue-and-cheek jokes, a little dirty humor snuck by censors for the enjoyment of any adults watching.

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Though these little in-jokes created some legendary cartoon moments, such as Ren & Stimpy's closet joke, Rocko's Modern Life's phone sex line, and of course Animaniacs' famous 'Fingerprints' line, cartoons have made sure never to cross certain lines. However, occasionally a romance came along that was so sweet, authentic, and endearing that even the artists themselves couldn't resist pushing the envelope of acceptable levels of steaminess for a cartoon. When this happened, it provided viewers, including kids, with brief moments of genuinely hot drawn lines and CGI images, at least in capacity of what drawn lines and CGI images can provide. As a side note: Anime shows won't be appearing on this list, that's an article for another day.

15 LADY RAINICORN LIKES BEING BITTEN (ADVENTURE TIME)

Adventure Time is an endlessly creative show chocked full of cute and dramatic romances and relationships. But the only one that seems to mirror realism is that between Jake the Dog and his wife Lady Rainicorn. Their flirtations were consistently sweet and personalized. Their most oblique flirt and steamiest moment came in the episode "From Bad to Worse" where everybody but Finn gets turned into a buff, winged, big-lipped zombie.

During the crisis, Jake is infected and attacks Lady Rainicorn. Later, when the status quo had been restored, Jake apologizes for biting his wife to which she replies "I wanted you to bite me." Jake's furious blush and nervous giggle leaves no guesses as to what the two mystic beings get up to in the bedroom.

14 NALA'S 'COME HITHER' LOOK (THE LION KING)

The Lion King, or Disney's Hamlet, will always be remembered for its stellar animation, fantastic voiceover performances, and this blink-and-you'll-miss-it moment where Nala looks like she wants to jump Simba's bones in front of an audience of children and parents. With the sultry strains of Elton John's "Can You Feel The Love Tonight" playing over the scene of two childhood friends reuniting, Nala delivers a sudden kiss to Simba's cheek, freezing him in place.

She then fixes him with a gaze that can only be described as 'Damn!' Though their subsequent coitus is only implied, this is possibly the closest Disney has ever come to showing their characters bump uglies. The fact that these characters are animated, and animals on top of that, does not differ from the raw sensuality exuded in these few frames.

13 KIF AND AMY'S FIRST DATE (FUTURAMA)

Of all of the interesting romances in Matt Groening's Futurama, the most intriguing was between the soft-spoken alien lieutenant Kif and ditzy intern Amy. Their strange but sincere relationship began in the episode "Amazon Women in the Mood" when a desperate Kif allows Zapp to organize a double date with Amy and Leela. Zapp's misogynistic dating advice initially seems to ruin Kif's chances with Amy, but he manages to save the date with an impassioned karaoke performance.

Their romance is cemented, but their intimacy is only brought up later after they are stranded on a planet of giant, amazonian women where Amy saves Kif from being 'snu-snued' to death. Kif asks Amy what they could do going forward and she responds with a knowing whisper in his ear which causes him to have a small panic attack, suggesting that what happens next is an inter-species game of hide the sausage.

12 "YOU NEED TO BE MORE...FLEXIBLE" (THE INCREDIBLES)

Pixar's The Incredibles is a fantastic movie about a lovable family of superheroes. The beginning of the film establishes that superheroes have been forced to retire and go underground, forming the origins of the family's inner conflicts. The origins of the family itself, however, are made more clear in a scene shared by mother Elastigirl and father Mr. Incredible. After simultaneously stopping a purse snatcher on the day of their wedding, the two heroes share a tender moment on a rooftop where they flirt and argue over who really 'got the criminal.'

When Elastigirl suggests they share the victory, Mr. Incredible declines, prompting Elastigirl to use her stretching and contorting powers to flip around his body while delivering the soft, sensual line, "You need to be more...flexible." The romantic atmosphere awash in red and orange lights combined with their shared chemistry and playful banter make for a steamy, intimate scene.

11 HAWKGIRL'S UNMASKING (JUSTICE LEAGUE UNLIMITED)

Justice League Unlimited was the expansion of Bruce Timm's lauded animated universe to include DC's eponymous super team. Though the focus of the series was mostly on character interaction and crime-fighting exploits, a significant subplot involved a budding romance between Green Lantern John Stewart and Hawkgirl. This culminated aboard the Justice League Watchtower after a rigmarole with the Joker and the Royal Flush Gang in Las Vegas.

Stewart was wounded in the battle and Hawkgirl brought him back to the Watchtower for medical treatment. When the ordeal was resolved, the two finally brought their feelings to the forefront as a shirtless Stewart slowly seduces her, belaying her concerns over their relationship. Hawkgirl allows him to take off her mask for the  first time in the series and viewers are treated to the image of them sharing a deep, sensual kiss.

10 NEW YEAR'S KISS (REGULAR SHOW)

Regular Show is essentially Cartoon Network's answer to It's Always Sunny in Philadelphia in that it too is about generally unlikable characters engaging in likable exploits. For example, the episode "New Year's Kiss" sees Rigby desperately trying to stop Mordecai from kissing his date at a New Year's party because his future self told him it would have negative consequences.

The entire episode shows the despicable lengths Rigby goes to to prevent his friend's happiness, but his efforts are for naught because Mordecai breaks up with his date before they lock lips. However, at the stroke of midnight, Mordecai shares a brief moment of vulnerability with an equally single masked girl. In a moment of impulse among a sea of couples, the two make out with reckless abandon. It is only after their kiss that Mordecai learns his mystery woman is actually CJ, one of his ex-girlfriends.

9 GARNET (STEVEN UNIVERSE)

Steven Universe has a unique approach to romantic relationships in the form of 'fusions' -- characters who are quite literally the product of two or more other characters physically molding together, mind, body, and soul. The principle example of fusion is the fan-favorite character Garnet, voice by Estelle. Presented as the leader of the show's hero faction for the majority of season one, it is eventually revealed that Garnet is the physical embodiment of the love shared between two other characters, Sapphire and Ruby.

They love each other so much that they exist in the constant state of fusion that is Garnet. The scene in the episode "Jail Break" where Sapphire and Ruby reunite and dance to reform Garnet is so sickeningly sweet and intimate that it is only topped in the series by the reveal of Garnet's origins in "The Answer".

8 POST-FIGHT MAKE OUT SESH (SAMURAI JACK)

The long awaited season five of Samurai Jack was supposed to be the ultimate return of a beloved character, but slowly revealed itself to actually be the story of Jack's failed romance with brainwashed assassin and Daughter of Aku, Ashi. Initially mortal enemies, the two are forced to cooperate in order to escape the stomach of a giant sea creature. After seeing Jack was not the diabolical evil she'd been raised to see him as, Ashi began the slow transition into Jack's ally and began teasing an attraction between the two.

Finally, after a partially-naked, hard-fought battle against an alien criminal where the two are left panting and covered in goop, they suddenly embrace and kiss while romantic music begins to play. The near-nudity and buildup to their kiss makes this one of the steamier, more explicit moments in recent cartoons.

7 ZUKO AND MAI'S PICNIC (AVATAR: THE LAST AIRBENDER)

Though the main romance of the series may have been Aang and Katara, the long-term romance between Prince Zuko and Mai was the most serious and realized. The turbulent, roller-coaster ride of a relationship rose and fell throughout the third season, but one of the more notable images of them together was a picnic they shared cliff-side at sunset after Zuko returned from exile.

Mai, ever the pessimistic downer, remarks on how ugly the sunset is. Zuko chuckles and appreciates how much she hates the world, to which she replies, "I don't hate you," which is basically as endearing a statement she can give. The lighting, mood music, seclusion, and passionate kiss they share suggest to viewers that what happens next wouldn't make it past Nickelodeon censors, except that any action that would have followed the picnic was interrupted by perpetual fun-killer Azula.

6 JUNIOR PROM (KIM POSSIBLE)

The whole crux of Kim Possible as a series was that the titular character was stuck trying to balance normal teenage girl problems with being a secret agent. Though for the most part, her relationship with sidekick Ron Stoppable was that of friends, but the show slowly began establishing a vague attraction between the two which was never fully explored until the made-for-TV movie So the Drama.

In it, Kim desperately looks for a date to the junior prom while fighting Dr. Drakken and generally discounting Ron. However, at the end of the night she is left with no choice but to take him as her date. During their dance, the two of them lock eyes and tentatively grow closer, eventually rounding first base in front of their entire school. The teenage setting and pop song played over it make for a nostalgic moment with defined sensual undertones.

5 PRISON KISS (YOUNG JUSTICE)

Young Justice was a well-received show about the young heroes in the DC Universe. One of the most popular elements of the cartoon was the steady build of a believable relationship between Superboy and Miss Martian. Though intimacy between the two had been teased before, the true explosion of their mutual attraction came in the episode "Terrors" where the two went undercover in the super prison Belle Reve.

Their mission was to prevent a prison break from setting loose dozens of super criminals, but during their efforts Miss Martian was frozen solid by Killer Frost. Heartbroken, Superboy mentally revealed his attraction to Miss Martian. Fortunately, Miss Martian had survived the ice attack and was greeted to a tender kiss from Superboy once she was freed. The desperation, relief, and ongoing danger of the atmosphere made their kiss all the more meaningful and physical.

4 WE'LL ALWAYS HAVE TOKYO (TEEN TITANS: TROUBLE IN TOKYO)

One of the best cartoons to come out of the mid-2000's, Teen Titans ended in spectacular fashion with the movie Trouble in Tokyo which not only saw the characters fully admit to the show's anime influences with a mission in the capital of Japan, but also finally confirmed the romance between team leader Robin and alien princess Starfire.

A famous couple in the original comics, their attraction had only been hinted at in the series proper, but the freedom of their series ending gave the writers the courage to show their relationship. When the mastermind villain is defeated, Robin finally attempts to admit his feelings. Clearly exhausted from their fight, Starfire simply instructs him to stop talking and kisses him. The intimacy of their kiss is enforced by rain animation and the dichromatic color schemes of the characters filling the screen.

3 BLACK CAT BEATS MJ TO THE PUNCH (SPECTACULAR SPIDER-MAN)

Though it may have been the most iconic scene from Sam Rami's Spider-Man the upside-down kiss was much more steamy when it was done by Black Cat in Spectacular Spider-Man. After briefly teaming with the symbiote-suited Spider-Man to stop a yacht robbery, the two meet up at a buttress where Spider-Man hangs in his signature head rush-inducing pose. After discussing the possibility of Black Cat being a hero, she pulls his mask down and goes for a smooch.

It lasts longer than necessary and the expansion of Spider-Man's eyes as he reacts to the sudden intimacy shows that the move wasn't unappreciated. But while Spider-Man is trying to process the kiss, Black Cat holds the precious gem she stole from the yacht behind his head, admiring her prize. The subtle animation and uneasy balance of motive and character make this moment more sensual and memorable than its live-action counterpart.

2 ALL OF HOMER AND MARGE (THE SIMPSONS)

Perhaps the greatest cartoon of all time and certainly the most prolific, The Simpsons is all about the dysfunctional family that centers around the irrevocable love between Homer and Marge Simpsons. No matter what shenanigans they or their family is put through, the two of them always manage to restore order through the sheer power of their affection for each other.

From renting a hotel and waterbed for a night away from the kids, to celebrating a raise with new negligee, to dropping some of the greatest pickup lines in television history in simple car rides, there hasn't been a single moment of intimacy between these two that hasn't been romantically avant garde.  Additionally, Groening has never been afraid to draw his characters in various states of undress, so little has been left to the imagination when it comes to what the Simpsons parents look like under the sheets.

1 JESSICA RABBIT (WHO FRAMED RODGER RABBIT)

Jessica Rabbit is far and away the sexiest picture ever drawn with pencil and paper. Every movement her impossibly-proportioned body makes, every sound that leaves her excessively plump lips, every flap of her shape-shifting dress, it's all meant to be as sensual and steamy as possible. From her introduction in a nightclub singing a saucy jazz number to suggestively promising to make her husband a 'carrot cake' at the end of the film, there's not a single second of her screen time that doesn't exude sheer sexuality.

A particularly throaty voice-over performance by Kathleen Turner certainly doesn't hurt. Bob Hoskins's shocked face when she emerges from behind the red curtains for the first time says it all, she's the male gaze and unrequited sexual attraction personified. As the lady herself puts it; "I'm not bad, I'm just drawn that way."

Did we miss out on any other hot cartoon-on-cartoon action? Let us know in the comments!