Extendable Ears - Long, flesh-coloured pieces of string which one can insert in one's ear, then shove the other end under (for example) a door, and one will hear the conversation or other noise. First seen in Harry Potter and the Order of the Phoenix
Ron: "Fred and George have invented Extendable Ears, see. They're
Ron: "Ears, yeah. Only we've had
to stop using them lately because Mum found out and went berserk."
Self-Inking, Spell-Checking, and Smart-Answer Quills - first appearance Harry Potter and the Half Blood Prince
Skiving Snackboxes (includes: Puking Pastilles, Fainting Fancies, Fever Fudge, and Nosebleed Nougat) - The user develops strange symptoms depending on the type of sweet eaten. The purpose of these were to make a student appear unable to stay in class. Most came in two colour-coded parts: one that would cause the malady, and one that would cure the pupil once they had left class. First seen in Harry Potter and the Order of the Phoenix
Hermione: "It is NOT excellent!"
Fred: "Course it is, they're alive,
Hermione: "You can't do this, what if you made one of
them really ill?"
Fred: "We're not going to make them ill, we've
already tested them all on ourselves, this is just to see if everyone
reacts the same —"
Canary Creams - They have the appearance and taste of ordinary custard creams, but when eaten, they transfigure the eater into a large canary. Within a minute, the person will molt his or her feathers and revert to normal. First seen in Harry Potter and the Goblet of Fire.
"Want a jam tart, Hermione? It’s all right. I haven’t done anything to
them. It’s the custard creams you’ve got to watch..." - Fred Weasley
Headless Hats - Small hats covered in pink feathers. When worn, the hat and head of the person wearing it, disappears. First appearnace in Harry Potter and the Order of the Phoenix.
"How do those hats work then? I mean, obviously it's some kind of
Invisibility Spell, but it's rather clever to have extended the field
of invisibility beyond the boundaries of the charmed object..." - Hermione Granger
Wildfire Whiz-bangs - Unstoppable fireworks that are charmed to explode when struck with a Stunning Spell, and to multiply by ten when hit with a Vanishing Charm. They include shocking-pink Catherine wheels, fire-breathing dragons, sparklers that spell out profanity, rockets with long tails of silver stars and firecrackers. When any two types collide, they make new kinds such as flying silver and pink pigs. First seen in Harry Potter and the Order of the Phoenix.
Hermione: "They were wonderful fireworks."
George: "Thanks. Weasleys' Wildfire Whiz-bangs. Only thing is, we used our whole stock; we’re going to have to start again from scratch now."
Fred: "It was worth
Ton-Tongue Toffee - a rainbow colored sweet with the power of the Engorgement Charm, makes the tongue of the consumer swell to an indeterminate size. First seen in Harry Potter and the Goblet of Fire
George Weasley: "How big did his tongue get?"
Arthur Weasley: "It was four feet long before his parents would let me shrink it."— after Dudley Dursley ate the toffe
Trick Wands - When used to cast a spell, they turn into random objects (e.g. rubber chickens). A more expensive version beats the user around the head and neck. First appearance Harry Potter and the Goblet of Fire
Patented Daydream Charms - Virtually undetectable, they produce a very realistic daydream lasting for thirty minutes. Side effects may include drooling and/or dazed expression. First appearance in Harry Potter and the Half Blood Prince
Punching telescopes - When it is squeezed, a tiny fist on a spring erupts from its end and lands a punch, accompanied by a puff of black smoke and a loud bang.1 The purple bruise caused by the telescope does not fade by itself, and cannot be healed with standard remedies. First seen in Harry Potter and the Half Blood Prince.
Fred: "And what's happened to your eye, Hermione?"
Hermione: "Your punching telescope."
Fred: "Oh, blimey, I forgot about those. Here... Just dab it on, that bruise'll >be gone within the hour. We had to find a decent bruise remover. We're testing most of our products on ourselves."
Guaranteed Ten-Second Pimple Vanisher - Comes in a small pink pot and is excellent on anything from boils to pimples and to blackheads. Its purpose is to immediately eliminate extreme face acne. First seen in Harry Potter and the Half Blood Prince.
WonderWitch love potions - A range of Love Potions that induce infatuation in the drinker for up to twenty-four hours, depending on the weight of the boy and attractiveness of the girl in question. Known potions in this range included: Beguiling Bubbles, Cupid Crystals, Heartbreak Teardrops, Kissing Concoction, Twilight Moonbeams, Calamity Lotion, Crush Blush, Love is Blind Eye Serum, Flirting Fancies
Reusable Hangman - Consisted of a small, wooden man which climbed the stairs leading to a set of gallows with every letter missed. First seen in Harry Potter and the Half Blood Prince.
Shield Gloves, Hats, and Cloaks
Pygmy Puffs - miniature Puffskein, bred in the back of the shop. First appearance in Harry Potter and the Half Blood Prince.
U-No-Poo - Causes constipation in the unknowing taker. The pills can be mashed up and mixed with food or drink. First appearance in Harry Potter and The Half Blood Prince.
WHY ARE YOU WORRYING ABOUT YOU-KNOW-WHO? YOU SHOULD BE WORRYING ABOUT
U-NO-POO THE CONSTIPATION SENSATION THAT'S GRIPPING THE NATION!"
—Advertisement poster in the window of Weasleys' Wizard Wheezes
Edible Dark Marks - sweets that were shaped like the Dark Mark. First seen in Harry Potter and the Half Blood Prince
Peruvian Instant Darkness Powder (was imported from Peru, as name suggests)
Decoy Detonators - black horn-like objects designed to create a diversion. After being dropped, the decoy runs a fair distance away, makes a noise like a loud bang, and releases clouds of black smoke, diverting attention from the user. - First appearance in Harry Potter and the Half Blood Prince.