Final answer:
The product 'Coughing Confectioneries' was not a Skiving Snackbox by the Weasley twins in the Harry Potter series; Puking Pastilles, Nosebleed Nougat, and Sneezy Sweets were actual products.
Step-by-step explanation:
The product that was NOT a Skiving Snackbox created by the Weasley twins is c. Coughing Confectioneries. Fred and George Weasley, characters in the Harry Potter series, introduced various magical products to help students skip classes. Some of the products included are Puking Pastilles, which caused the consumer to vomit; Nosebleed Nougat, inducing nosebleeds; and Sneezy Sweets, which caused sneezing. Coughing Confectioneries are not mentioned as part of their Skiving Snackboxes within the series.