Muggles' Guide to Harry Potter/Magic/Ton-Tongue Toffee

Overview
Ton-Tongue toffees are products of Weasleys' Wizard Wheezes that make the tongue of the person eating them become several feet long.

Extended Description
Possibly the start of the "Skiving Snackbox" line, this is an early Weasley's product that was first tested out on Harry's cousin Dudley in Harry Potter and the Goblet of Fire. This got the twins into a lot of trouble with their father and mother.

Analysis
Something of a throw-away idea, the Ton-Tongue Toffees are used to prank Dudley, and then are taken away and destroyed by Mrs. Weasley, and we never see them again. While they have physiological effects on the person eating them, and so could be placed in the Skiving Snackboxes line, the effects are not something that would require a visit to the Hospital wing, and so don't have a major part in the Twins' story.