It's quite amazing really – how fast things can escalate. A bowl filled with water is one of the simplest sights in the world yet all it takes is one tiny lump of potassium for the small sea to erupt in sparks and smoke, leaping purple bolts and hyena-like cackling all pouring out of this one bowl because a clump of metal was dropped in an inconsequential amount of water.
If one were to use this as an example for human or wizarding behaviour they would probably come to conclude that Fred and George Weasley were the largest, most reactive lumps of potassium Hogwarts School of witchcraft and wizardry had ever known.
The day had begun like any other with the school population gathering in the great hall for breakfast in their usual divide of house colours. The faculty sat at their higher table making small talk and keeping a disinterested watch over the students. So in indifferent were they that not one of them noticed the eager plotting of two red headed Gryffindor students or (and this does not speak well for the assertiveness of Hogwarts staff) even pay enough attention to see an odd looking green sweet vanish with a mysterious flash from the table of the red & gold wearing pupils. In fact; no one even saw the same green sweet fall with a small splash into the breakfast bowl of Hogwarts' high inquisitor, Dolores Umbridge just a half second as she turned to eavesdrop on something Professors Sprout and Flitwick were discussing.
However, everybody was paying attention when mere moments later the Ministry appointed teacher began to turn a bright shade of green; her eyes grew until they bulged out of her head, ears morphing into near invisible holes, nose shrinking, limbs shrinking, her whole body began to shrink!
The process of transformation only lasted for ten seconds but to the Hogwarts pupils it felt like hours before their least favourite teacher was nought but a slimy green toad hopping madly on the high table, though some students would later argue that no visible change occurred.
It was surprisingly a young Ravenclaw who first chose to seize this opportunity to strike revenge for Umbridge's wicked ways. Shooting a stunning spell right in the toad's direction, the spell was the first of many and before long the professors were frantically casting protegos to stop the incoming slew of stunners.
It was not long before the Slytherins, cunning snakes that they are, decided to use the sudden attack as a distraction to launch their own barricade of spells at the Gryffindors who, hot-headed lions that they are, matched the onslaught of hexes with a vicious firing towards their enemy house. Spells were now flying in every direction and the room was alight with fireworks they produced. The professors' panicked attempts to subdue the fights were a slow process due to the great outnumbering they were faced with.
Throughout the anarchy there were perhaps only four individuals in the entire hall who were thinking straight. The first two was the Headmaster and Deputy Headmistress who were using every transfiguration spell in their arsenal to try and reverse the magic placed on Umbridge; the second two would come as shock to many as the only two students wise enough to think straight during the chaos were none other than the Weasley twins.
The boys were hid under a table manically searching through their bags for a potion that would take revenge upon their former least favourite professor, Severus Snape. The potion in question was quite like the one they had used on Umbridge except it need only to be poured on the intended recipient, and would turn them into a bat as opposed to a toad. They figured they had less than a minute before Dumbledore stopped the mini-warfare and they fully intended to take advantage of the time to catch the potions professor of guard for once.
Unfortunately for them, or fortunately depending on the outlook the large bottle they dug out from their prank bag was not the human to animal transfiguration potion but an experimental love potion they'd given up on several months ago. The potion had been meant to make the drinker more appealing to their desired one and it worked in theory, once brewed a hair needed to be added from the desired one and the drinker would become instantly far more appealing to whosever hair had been added but there were several downfalls; for one thing the potion had no effect if the drinker and their desired were of the same gender, it also had no effect over the drinker's personality so if the desired only found them mentally unappealing the potion had nothing to fix, and lastly the potion was far too strong, once taken the drinker would not only become vastly different in appearance but the effects made it so their desired became obsessed with the drinker and would be intensely aroused whenever near them.
For this the twins had abandoned the experiment and cast it aside, never even bothering properly dispose of it. So when they lobbed the bottle towards a greasy head of hair and it smashed triumphantly coating the man with a dark gooey substance that seemed to grow until the (now unconscious) man was fully coated in the black goo they had no idea what they had absolutely no idea what was happening, and promptly ran from the hall, fearing the wrath of any staff who may have seen them throw the potion that had knocked out Snape.
It would be many hours before a thoroughly cleaned potion professor would awaken with a pained expression in the infirmary but by that time the twins would already have dismissed the incident as the transfiguration potion having been miss-brewed and the effects of the love potion were already irreversibly in place.