In today's culture, Thanksgiving is about two things - giving thanks and eating. This special is mainly concerned with the latter. Garfield goes through several traumas in this special, including the vet and an owner who can't cook. Listen for character actress Pat Caroll as Grandma.
This special is known to Garfield fans and people who were kids in the late 80's. It's available on DVD and can be seen in full on YouTube, thanks to an upload by GarfieldSpecials2011. Part one is above.
Obscurity factor: 6 (on DVD, known to Garfield fans, not generally known otherwise)