The beginning of summer term was rather quiet by normal Hogwarts standards, giving Harry and Hermione time to perfect a suggestion Fleur had given to them when they'd first become friends.
Once the French girl had found out that Harry had a perfect Invisibility Cloak, and Hermione was an era-defining genius, and there were a lot of annoying gits at the school that needed knocked down a level in a highly pleasurable but excruciatingly embarrassing way, she'd propositioned the two with an idea she'd been wanting to do for years at Beauxbatons, but didn't have the means or skills or necessary partner to implement. It had taken almost six months for Hermione to finally perfect the necessary spell, but at the beginning of May, after much testing and fiddling and practicing with Harry and Fleur in Fleur's carriage, and then with Harry, Sally, and Lavender in their dorm room, and finally with Harry, Fleur, Sally, and Lavender in the Gryffindor common room, she'd finally gotten it perfect.
Sitting down to supper one evening, Harry ducked under the table, pulling his invisibility cloak over him. Hermione scooted forwards to the very edge of her seat, spreading her legs wide. Lavender and Sally-Anne sat down on either side of her, and Fleur sat down across from them, just to make sure no one could see anything out of the ordinary going on under the table. They'd practiced this over and over in Hermione's dorm room and at a table in the corner of the Gryffindor common room, but it was a little less of an issue to be caught in either of those places than in the middle of the Great Hall.
Hermione casually cast the spell on her vagina, before looking around to see who she wanted to try it out on first. Millicent Bulstrode had been particularly nasty to her earlier that day in class, so with her wand still hidden under the table, she cast the other half of the spell at the busty Slytherin. Seeing the Snake's hair glow slightly gold for a second, she tapped Harry with her foot to let him know it was safe to start. So hidden by his invisibility cloak, he snuck up under Hermione's robes, where he could begin orally pleasuring her.
As Harry's tongue got to work, Hermione felt the pleasurable tingles begin building in her stomach. But unlike it normally would, it never reached the point where she'd start moaning, or even panting lightly. For instead, the extra pleasure beyond what could be considered decent in a public space, was being apparated elsewhere.
Meanwhile, across the hall, Millicent was squeezing her thighs tightly, wondering why the hell she'd just become hot and wet all of a sudden. But before she could really think about it, it felt like someone had stuck her favorite vibrator directly on her clit and a moan escaped her lips before she could stop it. Everyone around her turned and looked at her, causing her to blush as brightly as the marinara sauce they were having with their spaghetti that night.
"This is just really good spaghetti," she muttered weakly, squeezing her thighs together even tighter.
No one believed her in the least, as while all the food at Hogwarts was good, the spaghetti certainly wasn't orgasmic. But no one said anything, as stranger things routinely happened at Hogwarts, and which of the girls could honestly say they hadn't at least once stuck their favorite vibes up their pussies and tried to keep anyone from finding out during class or a meal?
As everyone returned to their meals, Millicent bit her lower lip and pulled a book out of her bag and laid it open on the table, so she could bury her mouth in her palm and just look like she was studying really intently. Once again, no one was buying it, having seen or done that move too many times to be fooled, but once again again, nobody commented on it as they really didn't care, or else were guilty of having done it before themselves.
The pleasure continued rolling in waves through the Slytherin, the insanely good vibrations sometimes working her clit and sometimes coming deep inside her cunt against her g-spot, and within five minutes, she was a quivering mess. If it hadn't been in the middle of the Great Hall during supper, and she knew where it was coming from, she would have enjoyed it quite immensely. As it was, she was just trying to hold it together and not embarrass herself any more than necessary.
But less than a minute later that became quite impossible, as a particularly hard surge hit her, and she tumbled over the edge shuttering, letting out a loud scream and moan that couldn't be misinterpreted as anything other than a girl coming very, very hard.
As everyone turned to stare at the Slytherin, and a few people (led by the twins) set up a hardy round of clapping, across the hall Hermione pushed Harry's head away from her nether regions, figuring it too cruel to let Harry continue attacking what she knew was now a very, very oversensitive clit. Harry had slipped off the invisibility cloak and nestled himself on the bench between Hermione and Sally by the time Millicent had finally stopped shaking and everyone had started returning to their meals.
Piling his plate high with food, Harry whispered with just a hint of a smirk, "Successful, I take it?"
"Quite," replied Hermione quietly. "Although you're going to have to drag me into a broom closet and fuck me properly as soon as we get done eating."
Sally then leaned across Harry, not bothering in the least to try to keep her body from bushing up against his as much as possible, to say to both of them, "Weren't you working on having it slightly delayed, so the pleasure had built up some before it transferred? Because I'm not sure all girls would stick it out like Millicent did, no matter how pleasurable the feelings are. Which whoo, buddy, they are. Harry's got one hell of a talented tongue."
"Benefits of being a parseltongue," smirked Harry in reply. "And everyone thought it was the end of the world second year, before completely forgetting it even existed."
Getting the discussion back on point, and away from the wizarding world's bigotry, Hermione said, "I do have a modified version of the spell that I think will do that. I just wanted to try out the standard version first, and make sure it would really work and we could pull it off. And if Milli had gotten up and left, the spell would have broke about the time she got out into the entrance hall, and I would have just cast it on someone else and tried again. But tomorrow night we can try the modified version. I think Ginny would be a good first target for that, as she probably won't even blush when an orgasm hits her out of nowhere. She'll probably just drag her robes down under her breasts and play with them and pinch her nipples in front of the entire hall, until one of the teachers drags her away to the hospital wing."
~HP~
The next day at lunch, they tried the spell for a second time.
They stuck with the standard spell, saving the hard-hitting spell until supper, when they could be assured that the maximum number of people would be in the Great Hall to enjoy the show Ginny was bound to put on for them. The first girl they tried it on was a seventh year Slytherin they'd seen bullying a first year student between classes earlier that morning. But after the first few stripes of Harry's tongue and one solid parseltongue deep inside Hermione's cunt, the girl had shakily left the hall, and according to the reports from Daphne and Tracey that they received later, had gone into the nearest bathroom and from the sounds of it thoroughly finger-fucked herself to multiple screaming orgasms.
The second girl they used it on was Pansy, who promptly slapped Draco across the face for presumably finger-fucking her under the table as soon as she felt the first sensations against her snatch. Their ensuing argument kept her from any embarrassing moans until she suddenly came without warning, screeching like a banshee and collapsing into her plate, making the entire hall wonder what it was with Slytherins orgasming at the dinner table these days.
Once again, none of the teachers made any mention about it or even seemed to talk to the two girls, though a rumor was started that someone had seen Snape's hand disappear into his robes during both exhibitions, though whether that was actually true or not no one ever knew.
But finally at supper, they were able to bring out the coup de grâce.
Ginny had just filled her plate with food when her pussy lit on fire. All of the Gryffindors who'd been in the common room on the fateful Saturday after the second task — so all of the Gryffindors — knew how lewd the Weasley could be when she orgasmed. But that evening, the rest of the castle found out as well. The girl didn't even have time to try to grab for her breasts or pussy before she descended into a cursing mess, but fortunately for everyone watching, Harry wasn't done after just one round.
Hearing the telltale signs that the redhead was cumming hard, Harry pulled his lips back from Hermione's clit, and plunged three fingers deep into the Bushy-haired Bookworm's snatch.
Down the table, finally coming down from her first high, Ginny felt another mind-blowing orgasm building up in the depths of her cunt, and without even thinking about where she was, or that maybe it wasn't the most appropriate action she could take, she yanked her obscenely low-cut robes down under her breasts, and began toying with them just as Hermione had predicted. What they hadn't predicted was that the girl would suddenly shove everything off the table in front of her, and climb up onto the table and lay down flat on her back, legs bent and spread wide so everyone down the table could see her soaking pink pussy, and everyone in the entire hall could see her kneading her breasts and pinching and tugging her nipples. The entire hall stared in wonder as the girl writhed on the table, soon letting out another scream that indicated she was having her second orgasm in five minutes, in case the massive squirting didn't make it obvious enough.
But as soon as she'd come down from that one, she finally let a hand go from her breasts, just to pull the hem of her robes up around her waist, so she could plunge four fingers into her pussy like it was nothing. By this point the entire student body had crowded around the Gryffindor table to watch the train wreck, unable to look away. Ginny's fingers plunged in and out of her cunt at a rate that made more than a few girls cringe, and she was soon wrecked by yet another spasming orgasm.
After that, it became difficult to distinguish one orgasm from the next. Reports varied from eight to over a dozen total orgasms in less than fifteen minutes before Professor McG finally descended from the head table and Wingardium Leviosa'd the youngest Weasley out of the Great Hall and up to the hospital, fearing much more could leave the girl with permanent brain damage.
As it was, it was three days before anyone saw Ginny again and she finally returned to classes, albeit noticeably hobbling for another week still.