Fappiano was a holiday celebrated on Melmac. It was much like the Thanksgiving we have on Earth, except for the fact that Melmacians put up a Fappiano tree and placed presents underneath it, much like we do at Christmas. Melmacians naturally ate cats at Fappiano, as we eat turkey at Thanksgiving. They would eat from the time they got up until they opened their presents.
Fappiano was mentioned in the episodes Turkey in the Straw: Part 1, and Turkey in the Straw: Part 2. The name "Fappiano" was actually the last name of one of the workers on the show. In 2012 there was a fappiano marathon.