lordjsnows:

A Skiving Snackbox is a range of sweets to make the user appear to be ill. They are among a range of products from Weasleys’ Wizard Wheezes by Fred and George Weasley. 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.