Fred and George have spent the summer inventing joke products such as fake wands and joke sweets, and plan to sell them at Hogwarts. Mrs Weasley was furious when she found a stack of order forms for Weasleys' Wizard Wheezes in their room earlier in the summer; she told them not to make any more of them, and burned all of the order forms.
Fred and George have been working hard all summer to expand their range of joke products. Their Skiving Snackboxes include Fainting Fancies, Nosebleed Nougat and Puking Pastilles, although they each need a bit of work. The twins have been testing the products on themselves, taking it in turn to be the guinea-pig.
The twins hope to be able to buy proper premises for their joke shop, but are running a mail-order service until they have a chance to look. They placed an advert about Weasleys' Wizard Wheezes in the Daily Prophet the previous week.
Fred and George pay first-year Gryffindor students to test their Fainting Fancies in the Gryffindor Common Room. One by one, as though hit over the head with an invisible mallet, they slump unconscious in their seats. The effects of the Fancies are reversed by eating a purple sweet, reviving them almost immediately.
Fred and George have expanded their range of joke products for their shop in Diagon Alley. Weasleys' Wizard Wheezes stands out among the dull shop fronts in Diagon Alley; the left-hand window is full of an assortment of revolving, popping, flashing, bouncing and shrieking goods. The right-hand window is covered with a gigantic poster, emblazoned with flashing yellow letters reading:
Why Are You Worrying About You-Know-Who? You SHOULD Be Worrying About U-NO-POO – the Constipation Sensation That’s Gripping the Nation!
The shop is packed with customers, with boxes piled up to the ceiling and shelves of their joke products. A smaller, darker room houses the twins' Defence Against the Dark Arts products.
The twins have created more trick wands, Self-Inking, Spell-Checking and Smart-Answer quills, and Edible Dark Mark sweets. One of their new products is Patented Daydream Charms, which require impressively advanced magic to create, and they also sell Love Potions.
The twins created a more serious line of products, almost by accident, after the Ministry of Magic expressed an interest in their Shield Hats, which protect the wearer with a Shield Charm. The Ministry of Magic bought five hundred of the hats for their support staff, and the twins have expanded the range to Shield Cloaks and Shield Gloves, as well as the cunning Decoy Detonators and Instant Darkness Powder.