"We want to experiment with Doxy venom for our Skiving Snackboxes."
-- George Weasley (OP6)
"And speaking of your Skiving Snackboxes ...you can't advertise for testers on the Gryffindor noticeboard."
-- Hermione Granger, Gryffindor Prefect (OP12)
A range of sweets to make the eater ill; each different category looks like a different type of sweet and causes a different kind of illness. Each sweet is colour-coded so that one end causes the illness and the other makes the effect lift (OP6).
- The Weasley Twins sold the Snackboxes through the Daily Prophet until they got their shop in Diagon Alley with gold Harry gave them (OP6, HBP6).
- Sweets included: Nosebleed Nougats, Fainting Fancies, Fever Fudge, and Puking Pastilles.
- Their selling point was that you could eat one of these sweets before class, then get sent to the hospital wing when the symptoms showed up. This came in handy for Umbridge's DADA class. The reactions became known as "Umbridge-itis" (OP30).
- Hermione was not amused when the Twins experimented on first year Gryffindor students, making them ill with Fainting Fancies: "One by one, as though hit over the head with an invisible mallet, the first-years were slumping unconscious in their seats" (OP13). However, it was through Hermione that the Twins discovered that murtlap essence was the cure for the boils from their Fever Fudge (she made some for Harry, who suggested it to Lee Jordan, who told the Twins) (OP26)
- There's no doubt the Twins were walking a fine line, since George accidentally gave Katie Bell a blood blisterpod for her nosebleed during a Quidditch Match and made it much worse (OP14).
- Eventually Hermione was won over by the possibilities of the Skiving Snackboxes, including Puking Pastilles and Nosebleed Nougats in her beaded bag when packing for extended Horcrux hunting with Harry (DH12).
The Weasley Twins are shown using the scientific method of experimentation to figure out what will cure each illness from the Skiving Snackbox sweets, using observations and whatever ingredients they could find. Unfortunately they first had to take turns poisoning each other, experimenting on first years, and nearly causing Katie Bell to bleed to death. While each end of the candy in the Snackboxes was the antidote for the other end, there's no doubt they would have been expelled in any other kind of school on earth.
skive = British slang - to avoid school or work + snackboxes = candy and treats
Ethical Problem: The rather outrageous behavior of the Twins with the Skiving Snackboxes during Harry's fifth year posed an ethical problem for their brother Ron, who had just become a Prefect. While Hermione, also a Prefect, stood up to the Twins and told them off about their use of dangerous candy on first years, Ron managed to just ignore the whole thing and let Hermione handle it.
"Ron rose halfway out of his chair, hovered uncertainly for a moment or two, then muttered to Harry, 'She's got it under control,' before sinking as low in his chair as his lanky frame permitted." (OP13)
Unlike Neville, who won an award in first year for standing up to his friends, Ron could not stand up to his brothers. And there's another clear parallel with Ron, Hermione and the Twins: in the chapter "Snape's Worst Memory" (OP28) when Harry saw the memory in the Pensieve, Remus Lupin - also made a Prefect in fifth year - would not stand up to the other Marauders when they were bullying Snape, while Lily Evans did.
Harry remembered Lupin saying back in Grimmauld Place that Dumbledore had made him prefect in the hope that he would be able to exercise some control
over James and Sirius… but in the Pensieve, he had sat there and let it all happen… (OP29)