Now that you're not 12, give this passage◊ from Chamber of Secrets a close read. Alas, in the final chapter it's revealed that Ginny walked in on Percy kissing his girlfriend.
The final book constantly refers back to Harry & Ginny's "final snatched moments in darkened corners of the castle" before he breaks up with her before going on his final quest. The same kind of quote gets used anytime there's a party or ball occurring in Hogwarts.
Don't forget the couples out in the bushes during the Yule Ball. There's a fairly hilarious moment when Snape is a bit confused to see Harry and Ron there — although they'd actually been eavesdropping on his conversation with Karkaroff.
Also from Goblet of Fire, when McGonagall lets the Trio use the Transfiguration classroom to practice Harry's new hexes because she was tired of "walking in on them" everywhere else in the castle.
From the same book, the wizard who insists on wearing robes instead of Muggle pants because he "likes a healthy breeze 'round my privates, thanks".
In Half-Blood Prince, the narration mentions that Harry was having dreams about Ginny that "made him devoutly thankful that Ron could not perform Legilimency". Wonder what kind of dreams he was having?
Let's face it, FenrirGreyback was a pedophile. Especially considering that Rowling used lycanthropy as a metaphor for AIDS, which makes him a pedophile looking to spread AIDS to children, not to mention Lupin's worry that he could pass his lycanthropy (as one passes HIV and other STDs) on to his son... and him, having been infected nearly his whole life, he probably did a fair bit of research on his condition that gave him good reason to fear this happening (i.e. he knows of a case where it has actually happened).
This snippet from the first book. This being the first book, it probably wasn't meant like this at all, but it sure as hell reads differently when you're in your teens or 20s as opposed to when you're eleven or twelve:
He pushed the door ajar and peered inside — and a horrible scene met his eyes. Snape and Filch were inside, alone. Snape was holding his robes above his knees.
Aberforth's illicit charms on goats could imply some sort of sexual activity. JKR was asked exactly what Aberforth had done with said goats at a Q&A session:
Fan: In the Goblet of Fire, Dumbledore said his brother was prosecuted for practicing inappropriate charms [JKR buries her head, to laughter] on a goat; what were the inappropriate charms he was practicing on that goat? JKR: How old are you? Fan: Eight. JKR: I think that he was trying to make a goat that was easy to keep clean [laughter], curly horns. That's a joke that works on a couple of levels. I really like Aberforth and his goats. But you know, Aberforth having this strange fondness for goats, if you've read book seven, came in really useful to Harry, later on, because a goat, a stag, you know. If you're a stupid Death Eater, what's the difference. So, that is my answer to YOU.
It was also wonderfully translated to Polish. Since there's not as much fun with the word "Uranus" in Poland, Mr. Polkowski had had to be quite inventive here. It went something like this (translated back to English from his translation to Polish):
Lavender: Oh Professor, look! I think I've got an unaspected planet! Oooh, which one's that, Professor? Prof. Trelawney: It is Uranus, my dear. A very important celestial body. Ron: Can I too have a look at Lavender's body?
Which would make it a Brick Joke, as in Half-Blood Prince, he totally does.
And the French translation changes it to the Moon. "Can I see your moon too, Lavender?" This does have the same connotations as the term "mooning" in English.
The Danish translation goes somewhat like this, with Ron's comment laden with Innuendo, since "end" can be understood as ass as well.
Lavender: Oh professor, I think my ending number got an unknown aspect, what can it be Professor? Prof Trevawnley: That's Uranus, dear. Ron: Can I see an aspect of your end as well Lavender?
And in OOTP, Ron uses basically the same joke again (though he isn't really in his right mind at the time):
Ron: Harry, we saw Uranus up close! (still giggling feebly) Get it, Harry? We saw Uranus. Ha ha ha.
Unfortunately, several other translations have completely missed these jokes, such as the Hungarian, Brazilian and Russian translations.
The Tales of Beedle the Bard is filled with cuddly Radio 4 innuendo in the sections where Dumbledore discusses the content of the fairy tales — particularly when he mentions a female relative refusing to marry a man after seeing him "fondle a Horklump" (a pink mushroom-like creature covered in bristles).
Deathly Hallows: Ginny was going to give Harry a birthday / farewell present to remember her by. It was in her bedroom, no gift boxes were evident, and it started with a deep kiss. Do the math on that one.
Especially since Harry's whole time at the Weasley's is played as if Harry is a soldier about to go to war (which he more or less is), and a lot of girlfriends and fiancee's made sure that their significant others ... considered themselves real men when they left, since they might not come back.
Ron, in the Half-Blood Prince film, shortly after Harry and Ginny return from the Room of Requirement:
Ron: So. Did you and Ginny do it? Harry:(taken aback) What!? Ron: You know. Hide the book. Harry: Oh. Yeah.
In the same movie, there's Ginny going down on Harry. And by that, we mean kneeling in front of him... to tie his shoe.
In Half-Blood Prince, Ron and Lavender stumble into a classroom where Harry is trying to comfort a distressed Hermione. Seeing as Ron and Lavender were perfectly comfortable making out rather passionately in a crowded common room, one has to wonder (or not) exactly why they suddenly felt the need to seek out an empty room. To clarify, the reason why Ron and Lavender didn't just use the mostly-empty room they found is obvious; Ron didn't want to see a distressed Hermione. Why they left the common room in the first place, however, is a mystery...
How about the spell-checking quill Ron uses to write his essay? "Augury" really doesn't start with O-R-G....
Worse in the Dutch translation; it actually fully spells out O-R-G-I-E (Dutch for orgy). How the translator ever got away with that, we'll never know.
The Danish translation makes him spell "rÝvsur" which is a slightly vulgar Danish expression for being very grumpy ("rÝv" means "ass").
HBP was chock full of this. The film in particular. Right after Dumbledore whisks Harry away from the cafe, he says something to the effect of, "I fear I may have robbed you of a wonderful evening." Note that Dumbledore's sort of implied to be able to see people's thoughts — not such a far-fetched idea given his own skill and the existence of Legilimency. And it's hard to think that, given the context, the girl's comment of "I get off at 11" wasn't a Double Entendre...
While most cases of profanity before Deathly Hallows were carefully written around, Prisoner of Azkaban makes use of an extended metaphor involving dogs and Harry's nature to have Aunt Marge call Harry's mother a bitch.
If there's something rotten on the inside, there's nothing anyone can do about it. ...It's one of the basic rules of breeding. You see it all the time with dogs. If there's something wrong with the bitch, there'll be something wrong with the pup... (insert Harry's accidental anger magic here). (later) Now, I'm saying nothing against your family, Petunia, but your sister was a bad egg. They turn up in the best families. Then she ran off with a wastrel and here's the result right in front of us.
And between the two is an explicit statement about killing weak dogs, like Harry.
How about Voldemort taking Lucius's wand in Deathly Hallows and comparing its length to his own wand's? And in the movie, rather than doing that, he strokes the damn thing, and while doing so, his eyelids flutter shut!! Also, the way Lucius winces when he snaps the handle off...
Feel free to laugh along. Ralph Fiennes' flamboyant portrayal of Voldemort was ENTIRELY intentional.
It's worth noting that Lucius' wand, according to source materials, is eighteen inches long, making it by a wide margin one of the longest known wands in the Potterverse. Cue the jokes about Compensating for Something...
On the other hand, remember that "The wand chooses the wizard". Maybe Lucius actually has nothing to compensate for?
"Well?" Ron said finally, looking up at Harry. "How was it?" Harry considered for a moment. "Wet," he said truthfully. Ron made a noise that might have indicated jubilation or disgust, it was hard to tell.
OK, Cho was crying because she remembered Cedric. The point was Ron's reaction.
We all know what Lavender thought Ron and Hermione had been doing when she caught them coming out of the boys' dormitory together. Of course, they weren't doing that, but the book still discreetly avoids mentioning exactly what Lavender must have been thinking upon seeing her boyfriend exit a bedroom with a girl he has an obvious crush on.
In Book 5, during the DA members-to-be meeting inside Hog's Head, Zacharias Smith, who Ron and Hermione both agree to dislike, keeps hounding Harry annoyingly, to the point the Weasley twins intercept with this:
"Would you like us to clean out your ears for you?" inquired George, pulling a long and lethal-looking metal instrument from inside one of the Zonko's bags. "Or any part of your body, really, we're not fussy where we stick this," said Fred.
In Prisoner of Azkaban, the security trolls assigned to guard Gryffindor Tower are described as "comparing the size of their clubs".
In the Prisoner of Azkaban film, during the credits (which are designed to look like the Maurader's Map), there are two pairs of feet in the corner◊... overlapping. It also helps that if you look close the *ahem* outside pair of feet clearly squeeze in and out.
The wand-weighting scene in Goblet of Fire. Specifically, the talk about polishing.
In Half-Blood Prince, after Christmas, the password to Gryffindor Tower is changed to "Abstinence". The chapter before had Ron admitting that he and Lavender "don't talk much. It's mainly..." "Snogging." Though, "abstinence" doesn't simply refer to not having sex. It can also mean refraining from drinking liquor, which is ironic, given that half the time she has page-time, the Fat Lady is drunk, and in that scene, the Fat Lady is massively hungover. It could also mean that the Fat Lady herself did something that she regretted, and decided to use that password as a reminder to lay off the booze. (Wasn't that just after Hermione told the boys the Fat Lady and her friend had drunk their way through several barrels of wine? Abstinence, indeed!)
Cracked did an article about the most depraved sex scenes implied in the series.
In Half-Blood Prince, Harry and his friends visit Fred and Georges' new shop. One of the products on sale is a magical daydream-creator, guaranteed to put the user into a hallucination to pass the time during class. There's a label stating that these are not for sale to anybody below sixteen. Wow, Mrs. Rowling. Everybody knows what 16-year olds will be daydreaming about... If You Know What I Mean. Real subtle.
Keep in mind that this is basically a drug with a more family friendly name. Also, as the Cracked article above points out, Amortentia, Love Potion, is, essentially, a magical date-rape drug. They distribute thisopenly. And, in fact, it was actually used to kidnap and rape someone; Voldemort's father.
6 Horrifying Implications of the Harry Potter Universe, again from Cracked. Relatively tame deconstruction of the Rowling world-building foibles, right up until we get to #2: the Marauder's Map and its total disregard for privacy: two issues are discussed are how it's entirely likely Fred and George knew the map identified Scabbers as Peter, and that in the credits of the third movie, there's an easter egg where two students are shagging in the corner. Also, #1, which uses the lack of privacy as a point of departure to springboard into the darker elements of magic. To give an example, Cracked draws a solid connection between Love Potions and Date Rape drugs.
There was also Ron's line about "not wanting people saying his sister's a—" regarding her many boyfriends.
And in book four, with him worrying about Hermione being known as a "scarlet woman". Which was arguably pretty funny.
In the muggle cafe at the beginning of Deathly Hallows, Hermione "muttered where exactly Ron could stick his wand."
Mandrakes "grow up" similarly to humans, going through puberty, etc. Then this happens: "The moment they start trying to move into each other's pots, we'll know they're fully mature."
There's multiple "Ron made a rude hand gesture" quotes.
There are also two occasions when Harry thinks someone else is making a rude hand gesture. In one case, Peter Pettigrew is using his middle finger to point and in the other, Marvolo Gaunt is showing Ogden the ring on his middle finger. You need an IQ of 3 to figure out the rude hand gesture.
One of the go-to interjections in the Potterverse is for wizards to swear by "Merlin's beard." Book 7 shows some of the cast getting a bit more creative with these, culminating in a moment where an irritated Ron asks, "Why in the name of Merlin's saggy left-" before his father cuts him off. Now, this could have been an innocuous body part like an eye or an arm... but then, this is Ron we're talking about, and if it were something more innocent, JKR wouldn't have felt the need to make use of a classic Curse Cut Short trope. Make of that what you will.