"You dropped it on purpose! ...You knew he'd eat it, you knew he was on a diet - ... That sort of behavior seriously undermines
-- Arthur Weasley to the Twins (GF5)
A magical joke candy.
Imbued with an Engorgement Charm, these sweets make a person's tongue swell up to ten times its normal size. It took six months for the twins to develop them, which didn't please their mother as they were supposed to have been studying for their O.W.L.s at the time. Molly confiscated the rest of the Ton-Tongue Toffees using the Summoning Charm "Accio" (GF4,GF5).
- What the Weasley Twins did to Dudley by enlarging his tongue was despicable, but they saw it as justice for Harry against a "great bullying git" (GF5). That was not the first time that Dudley was targeted by a wizard sympathetic to Harry, since Hagrid once zapped him with a pig's tail jinx (PS4). These episodes of Transfiguration made the Dursleys resent Harry even more, and to blame him when Dudley was attacked by a Dementor even though Harry saved him with his Patronus (OP1). Also the fat-shaming of Dudley is rather more cringeworthy because Petunia had put him on a lettuce diet while Harry had four cakes hidden under the floorboard of his bedroom (GF3).
- Soon after leaving the Dursleys in Goblet of Fire, Harry and the Weasleys stayed at the Quidditch World Cup campground where Lord Voldemort's Dark Mark appeared in the sky: "a colossal skull, comprised of what looked like emerald stars, with a serpent protruding from its mouth like a tongue" that resembled the statue of Salazar Slytherin in the Chamber of Secrets (GF9). Dudley's predicament with the Ton-Tongue Toffee seems to foreshadow that scene, with "Dudley's tongue lolling around like a great slimy python" as Harry left Privet Drive by Floo network "in a rush of emerald-green flames" (GF4).